These are intended to replace prepare_write and commit_write with more
flexible alternatives that are also able to avoid the buffered write
deadlock problems efficiently (which prepare_write is unable to do).
[mark.fasheh@oracle.com: API design contributions, code review and fixes]
[akpm@linux-foundation.org: various fixes]
[dmonakhov@sw.ru: new aop block_write_begin fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Dmitriy Monakhov <dmonakhov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an iterator data structure to operate over an iovec. Add usercopy
operators needed by generic_file_buffered_write, and convert that function
over.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Modify the core write() code so that it won't take a pagefault while holding a
lock on the pagecache page. There are a number of different deadlocks possible
if we try to do such a thing:
1. generic_buffered_write
2. lock_page
3. prepare_write
4. unlock_page+vmtruncate
5. copy_from_user
6. mmap_sem(r)
7. handle_mm_fault
8. lock_page (filemap_nopage)
9. commit_write
10. unlock_page
a. sys_munmap / sys_mlock / others
b. mmap_sem(w)
c. make_pages_present
d. get_user_pages
e. handle_mm_fault
f. lock_page (filemap_nopage)
2,8 - recursive deadlock if page is same
2,8;2,8 - ABBA deadlock is page is different
2,6;b,f - ABBA deadlock if page is same
The solution is as follows:
1. If we find the destination page is uptodate, continue as normal, but use
atomic usercopies which do not take pagefaults and do not zero the uncopied
tail of the destination. The destination is already uptodate, so we can
commit_write the full length even if there was a partial copy: it does not
matter that the tail was not modified, because if it is dirtied and written
back to disk it will not cause any problems (uptodate *means* that the
destination page is as new or newer than the copy on disk).
1a. The above requires that fault_in_pages_readable correctly returns access
information, because atomic usercopies cannot distinguish between
non-present pages in a readable mapping, from lack of a readable mapping.
2. If we find the destination page is non uptodate, unlock it (this could be
made slightly more optimal), then allocate a temporary page to copy the
source data into. Relock the destination page and continue with the copy.
However, instead of a usercopy (which might take a fault), copy the data
from the pinned temporary page via the kernel address space.
(also, rename maxlen to seglen, because it was confusing)
This increases the CPU/memory copy cost by almost 50% on the affected
workloads. That will be solved by introducing a new set of pagecache write
aops in a subsequent patch.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hide some of the open-coded nr_segs tests into the iovec helpers. This is all
to simplify generic_file_buffered_write, because that gets more complex in the
next patch.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Quite a bit of code is used in maintaining these "cached pages" that are
probably pretty unlikely to get used. It would require a narrow race where
the page is inserted concurrently while this process is allocating a page
in order to create the spare page. Then a multi-page write into an uncached
part of the file, to make use of it.
Next, the buffered write path (and others) uses its own LRU pagevec when it
should be just using the per-CPU LRU pagevec (which will cut down on both data
and code size cacheline footprint). Also, these private LRU pagevecs are
emptied after just a very short time, in contrast with the per-CPU pagevecs
that are persistent. Net result: 7.3 times fewer lru_lock acquisitions required
to add the pages to pagecache for a bulk write (in 4K chunks).
[this gets rid of some cond_resched() calls in readahead.c and mpage.c due
to clashes in -mm. What put them there, and why? ]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If prepare_write fails with AOP_TRUNCATED_PAGE, or if commit_write fails, then
we may have failed the write operation despite prepare_write having
instantiated blocks past i_size. Fix this, and consolidate the trimming into
one place.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow CONFIG_DEBUG_VM to switch off the prefaulting logic, to simulate the
Makes the race much easier to hit.
This is useful for demonstration and testing purposes, but is removed in a
subsequent patch.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename some variables and fix some types.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 6527c2bdf1, which
fixed the following bug:
When prefaulting in the pages in generic_file_buffered_write(), we only
faulted in the pages for the firts segment of the iovec. If the second of
successive segment described a mmapping of the page into which we're
write()ing, and that page is not up-to-date, the fault handler tries to lock
the already-locked page (to bring it up to date) and deadlocks.
An exploit for this bug is in writev-deadlock-demo.c, in
http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz.
(These demos assume blocksize < PAGE_CACHE_SIZE).
The problem with this fix is that it takes the kernel back to doing a single
prepare_write()/commit_write() per iovec segment. So in the worst case we'll
run prepare_write+commit_write 1024 times where we previously would have run
it once. The other problem with the fix is that it fix all the locking problems.
<insert numbers obtained via ext3-tools's writev-speed.c here>
And apparently this change killed NFS overwrite performance, because, I
suppose, it talks to the server for each prepare_write+commit_write.
So just back that patch out - we'll be fixing the deadlock by other means.
Nick says: also it only ever actually papered over the bug, because after
faulting in the pages, they might be unmapped or reclaimed.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 81b0c87133, which was
a bugfix against 6527c2bdf1 ("[PATCH]
generic_file_buffered_write(): deadlock on vectored write"), which we
also revert.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert the patch from Neil Brown to optimise NFSD writev handling.
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While running some memory intensive load, system response deteriorated just
after swap-out started.
The cause of this problem is that when a PG_reclaim page is moved to the tail
of the inactive LRU list in rotate_reclaimable_page(), lru_lock spin lock is
acquired every page writeback . This deteriorates system performance and
makes interrupt hold off time longer when swap-out started.
Following patch solves this problem. I use pagevec in rotating reclaimable
pages to mitigate LRU spin lock contention and reduce interrupt hold off time.
I did a test that allocating and touching pages in multiple processes, and
pinging to the test machine in flooding mode to measure response under memory
intensive load.
The test result is:
-2.6.23-rc5
--- testmachine ping statistics ---
3000 packets transmitted, 3000 received, 0% packet loss, time 53222ms
rtt min/avg/max/mdev = 0.074/0.652/172.228/7.176 ms, pipe 11, ipg/ewma
17.746/0.092 ms
-2.6.23-rc5-patched
--- testmachine ping statistics ---
3000 packets transmitted, 3000 received, 0% packet loss, time 51924ms
rtt min/avg/max/mdev = 0.072/0.108/3.884/0.114 ms, pipe 2, ipg/ewma
17.314/0.091 ms
Max round-trip-time was improved.
The test machine spec is that 4CPU(3.16GHz, Hyper-threading enabled)
8GB memory , 8GB swap.
I did ping test again to observe performance deterioration caused by taking
a ref.
-2.6.23-rc6-with-modifiedpatch
--- testmachine ping statistics ---
3000 packets transmitted, 3000 received, 0% packet loss, time 53386ms
rtt min/avg/max/mdev = 0.074/0.110/4.716/0.147 ms, pipe 2, ipg/ewma 17.801/0.129 ms
The result for my original patch is as follows.
-2.6.23-rc5-with-originalpatch
--- testmachine ping statistics ---
3000 packets transmitted, 3000 received, 0% packet loss, time 51924ms
rtt min/avg/max/mdev = 0.072/0.108/3.884/0.114 ms, pipe 2, ipg/ewma 17.314/0.091 ms
The influence to response was small.
[akpm@linux-foundation.org: fix uninitalised var warning]
[hugh@veritas.com: fix locking]
[randy.dunlap@oracle.com: fix function declaration]
[hugh@veritas.com: fix BUG at include/linux/mm.h:220!]
[hugh@veritas.com: kill redundancy in rotate_reclaimable_page]
[hugh@veritas.com: move_tail_pages into lru_add_drain]
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow an application to query the memories allowed by its context.
Updated numa_memory_policy.txt to mention that applications can use this to
obtain allowed memories for constructing valid policies.
TODO: update out-of-tree libnuma wrapper[s], or maybe add a new
wrapper--e.g., numa_get_mems_allowed() ?
Also, update numa syscall man pages.
Tested with memtoy V>=0.13.
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current VM can get itself into trouble fairly easily on systems with a
small ZONE_HIGHMEM, which is common on i686 computers with 1GB of memory.
On one side, page_alloc() will allocate down to zone->pages_low, while on
the other side, kswapd() and balance_pgdat() will try to free memory from
every zone, until every zone has more free pages than zone->pages_high.
Highmem can be filled up to zone->pages_low with page tables, ramfs,
vmalloc allocations and other unswappable things quite easily and without
many bad side effects, since we still have a huge ZONE_NORMAL to do future
allocations from.
However, as long as the number of free pages in the highmem zone is below
zone->pages_high, kswapd will continue swapping things out from
ZONE_NORMAL, too!
Sami Farin managed to get his system into a stage where kswapd had freed
about 700MB of low memory and was still "going strong".
The attached patch will make kswapd stop paging out data from zones when
there is more than enough memory free. We do go above zone->pages_high in
order to keep pressure between zones equal in normal circumstances, but the
patch should prevent the kind of excesses that made Sami's computer totally
unusable.
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmalloc() returns a void pointer, so there's no need to cast its
return value in mm/page_alloc.c::zone_wait_table_init().
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A NULL pointer means that the object was not allocated. One cannot
determine the size of an object that has not been allocated. Currently we
return 0 but we really should BUG() on attempts to determine the size of
something nonexistent.
krealloc() interprets NULL to mean a zero sized object. Handle that
separately in krealloc().
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The calculation of pgoff in do_linear_fault() should use PAGE_SHIFT and not
PAGE_CACHE_SHIFT since vma->vm_pgoff is in units of PAGE_SIZE and not
PAGE_CACHE_SIZE. At the moment linux/pagemap.h has PAGE_CACHE_SHIFT
defined as PAGE_SHIFT, but should that ever change this calculation would
break.
Signed-off-by: Dean Nelson <dcn@sgi.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Considering kfree(NULL) would normally occur only in error paths and
kfree(ZERO_SIZE_PTR) is uncommon as well, so let's use unlikely() for the
condition check in SLUB's and SLOB's kfree() to optimize for the common
case. SLAB has this already.
Signed-off-by: Satyam Sharma <satyam@infradead.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__add_to_swap_cache unconditionally sets the page locked, which can be a bit
alarming to the unsuspecting reader: in the code paths where the page is
visible to other CPUs, the page should be (and is) already locked.
Instead, just add a check to ensure the page is locked here, and teach the one
path relying on the old behaviour to call SetPageLocked itself.
[hugh@veritas.com: locking fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
find_lock_page does not need to recheck ->index because if the page is in the
right mapping then the index must be the same. Also, tree_lock does not need
to be retaken after the page is locked in order to test that ->mapping has not
changed, because holding the page lock pins its mapping.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Probing pages and radix_tree_tagged are lockless operations with the lockless
radix-tree. Convert these users to RCU locking rather than using tree_lock.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The commit b5810039a5 contains the note
A last caveat: the ZERO_PAGE is now refcounted and managed with rmap
(and thus mapcounted and count towards shared rss). These writes to
the struct page could cause excessive cacheline bouncing on big
systems. There are a number of ways this could be addressed if it is
an issue.
And indeed this cacheline bouncing has shown up on large SGI systems.
There was a situation where an Altix system was essentially livelocked
tearing down ZERO_PAGE pagetables when an HPC app aborted during startup.
This situation can be avoided in userspace, but it does highlight the
potential scalability problem with refcounting ZERO_PAGE, and corner
cases where it can really hurt (we don't want the system to livelock!).
There are several broad ways to fix this problem:
1. add back some special casing to avoid refcounting ZERO_PAGE
2. per-node or per-cpu ZERO_PAGES
3. remove the ZERO_PAGE completely
I will argue for 3. The others should also fix the problem, but they
result in more complex code than does 3, with little or no real benefit
that I can see.
Why? Inserting a ZERO_PAGE for anonymous read faults appears to be a
false optimisation: if an application is performance critical, it would
not be doing many read faults of new memory, or at least it could be
expected to write to that memory soon afterwards. If cache or memory use
is critical, it should not be working with a significant number of
ZERO_PAGEs anyway (a more compact representation of zeroes should be
used).
As a sanity check -- mesuring on my desktop system, there are never many
mappings to the ZERO_PAGE (eg. 2 or 3), thus memory usage here should not
increase much without it.
When running a make -j4 kernel compile on my dual core system, there are
about 1,000 mappings to the ZERO_PAGE created per second, but about 1,000
ZERO_PAGE COW faults per second (less than 1 ZERO_PAGE mapping per second
is torn down without being COWed). So removing ZERO_PAGE will save 1,000
page faults per second when running kbuild, while keeping it only saves
less than 1 page clearing operation per second. 1 page clear is cheaper
than a thousand faults, presumably, so there isn't an obvious loss.
Neither the logical argument nor these basic tests give a guarantee of no
regressions. However, this is a reasonable opportunity to try to remove
the ZERO_PAGE from the pagefault path. If it is found to cause regressions,
we can reintroduce it and just avoid refcounting it.
The /dev/zero ZERO_PAGE usage and TLB tricks also get nuked. I don't see
much use to them except on benchmarks. All other users of ZERO_PAGE are
converted just to use ZERO_PAGE(0) for simplicity. We can look at
replacing them all and maybe ripping out ZERO_PAGE completely when we are
more satisfied with this solution.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus "snif" Torvalds <torvalds@linux-foundation.org>
This gets rid of all kmalloc caches larger than page size. A kmalloc
request larger than PAGE_SIZE > 2 is going to be passed through to the page
allocator. This works both inline where we will call __get_free_pages
instead of kmem_cache_alloc and in __kmalloc.
kfree is modified to check if the object is in a slab page. If not then
the page is freed via the page allocator instead. Roughly similar to what
SLOB does.
Advantages:
- Reduces memory overhead for kmalloc array
- Large kmalloc operations are faster since they do not
need to pass through the slab allocator to get to the
page allocator.
- Performance increase of 10%-20% on alloc and 50% on free for
PAGE_SIZEd allocations.
SLUB must call page allocator for each alloc anyways since
the higher order pages which that allowed avoiding the page alloc calls
are not available in a reliable way anymore. So we are basically removing
useless slab allocator overhead.
- Large kmallocs yields page aligned object which is what
SLAB did. Bad things like using page sized kmalloc allocations to
stand in for page allocate allocs can be transparently handled and are not
distinguishable from page allocator uses.
- Checking for too large objects can be removed since
it is done by the page allocator.
Drawbacks:
- No accounting for large kmalloc slab allocations anymore
- No debugging of large kmalloc slab allocations.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The local copy of ra in do_generic_mapping_read() can now go away.
It predates readanead(req_size). In a time when the readahead code was called
on *every* single page. Hence a local has to be made to reduce the chance of
the readahead state being overwritten by a concurrent reader. More details
in: Linux: Random File I/O Regressions In 2.6
<http://kerneltrap.org/node/3039>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a simplified version of the pagecache context based readahead. It
handles the case of multiple threads reading on the same fd and invalidating
each others' readahead state. It does the trick by scanning the pagecache and
recovering the current read stream's readahead status.
The algorithm works in a opportunistic way, in that it does not try to detect
interleaved reads _actively_, which requires a probe into the page cache
(which means a little more overhead for random reads). It only tries to
handle a previously started sequential readahead whose state was overwritten
by another concurrent stream, and it can do this job pretty well.
Negative and positive examples(or what you can expect from it):
1) it cannot detect and serve perfect request-by-request interleaved reads
right:
time stream 1 stream 2
0 1
1 1001
2 2
3 1002
4 3
5 1003
6 4
7 1004
8 5
9 1005
Here no single readahead will be carried out.
2) However, if it's two concurrent reads by two threads, the chance of the
initial sequential readahead be started is huge. Once the first sequential
readahead is started for a stream, this patch will ensure that the readahead
window continues to rampup and won't be disturbed by other streams.
time stream 1 stream 2
0 1
1 2
2 1001
3 3
4 1002
5 1003
6 4
7 5
8 1004
9 6
10 1005
11 7
12 1006
13 1007
Here stream 1 will start a readahead at page 2, and stream 2 will start its
first readahead at page 1003. From then on the two streams will be served
right.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Combine the file_ra_state members
unsigned long prev_index
unsigned int prev_offset
into
loff_t prev_pos
It is more consistent and better supports huge files.
Thanks to Peter for the nice proposal!
[akpm@linux-foundation.org: fix shift overflow]
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fold file_ra_state.mmap_hit into file_ra_state.mmap_miss and make it an int.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use 'unsigned int' instead of 'unsigned long' for readahead sizes.
This helps reduce memory consumption on 64bit CPU when a lot of files are
opened.
CC: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch cleans up duplicate includes in
mm/
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert the common vmemmap population into initialisation helpers for use by
architecture vmemmap populators. All architecture implementing the
SPARSEMEM_VMEMMAP variant supply an architecture specific vmemmap_populate()
initialiser, which may make use of the helpers.
This allows us to clean up and remove the initialisation Kconfig entries.
With this patch there is a single SPARSEMEM_VMEMMAP_ENABLE Kconfig option to
indicate use of that variant.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SPARSEMEM is a pretty nice framework that unifies quite a bit of code over all
the arches. It would be great if it could be the default so that we can get
rid of various forms of DISCONTIG and other variations on memory maps. So far
what has hindered this are the additional lookups that SPARSEMEM introduces
for virt_to_page and page_address. This goes so far that the code to do this
has to be kept in a separate function and cannot be used inline.
This patch introduces a virtual memmap mode for SPARSEMEM, in which the memmap
is mapped into a virtually contigious area, only the active sections are
physically backed. This allows virt_to_page page_address and cohorts become
simple shift/add operations. No page flag fields, no table lookups, nothing
involving memory is required.
The two key operations pfn_to_page and page_to_page become:
#define __pfn_to_page(pfn) (vmemmap + (pfn))
#define __page_to_pfn(page) ((page) - vmemmap)
By having a virtual mapping for the memmap we allow simple access without
wasting physical memory. As kernel memory is typically already mapped 1:1
this introduces no additional overhead. The virtual mapping must be big
enough to allow a struct page to be allocated and mapped for all valid
physical pages. This vill make a virtual memmap difficult to use on 32 bit
platforms that support 36 address bits.
However, if there is enough virtual space available and the arch already maps
its 1-1 kernel space using TLBs (f.e. true of IA64 and x86_64) then this
technique makes SPARSEMEM lookups even more efficient than CONFIG_FLATMEM.
FLATMEM needs to read the contents of the mem_map variable to get the start of
the memmap and then add the offset to the required entry. vmemmap is a
constant to which we can simply add the offset.
This patch has the potential to allow us to make SPARSMEM the default (and
even the only) option for most systems. It should be optimal on UP, SMP and
NUMA on most platforms. Then we may even be able to remove the other memory
models: FLATMEM, DISCONTIG etc.
[apw@shadowen.org: config cleanups, resplit code etc]
[kamezawa.hiroyu@jp.fujitsu.com: Fix sparsemem_vmemmap init]
[apw@shadowen.org: vmemmap: remove excess debugging]
[apw@shadowen.org: simplify initialisation code and reduce duplication]
[apw@shadowen.org: pull out the vmemmap code into its own file]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have flags to indicate whether a section actually has a valid mem_map
associated with it. This is never set and we rely solely on the present bit
to indicate a section is valid. By definition a section is not valid if it
has no mem_map and there is a window during init where the present bit is set
but there is no mem_map, during which pfn_valid() will return true
incorrectly.
Use the existing SECTION_HAS_MEM_MAP flag to indicate the presence of a valid
mem_map. Switch valid_section{,_nr} and pfn_valid() to this bit. Add a new
present_section{,_nr} and pfn_present() interfaces for those users who care to
know that a section is going to be valid.
[akpm@linux-foundation.org: coding-syle fixes]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SPARSEMEM is a pretty nice framework that unifies quite a bit of code over all
the arches. It would be great if it could be the default so that we can get
rid of various forms of DISCONTIG and other variations on memory maps. So far
what has hindered this are the additional lookups that SPARSEMEM introduces
for virt_to_page and page_address. This goes so far that the code to do this
has to be kept in a separate function and cannot be used inline.
This patch introduces a virtual memmap mode for SPARSEMEM, in which the memmap
is mapped into a virtually contigious area, only the active sections are
physically backed. This allows virt_to_page page_address and cohorts become
simple shift/add operations. No page flag fields, no table lookups, nothing
involving memory is required.
The two key operations pfn_to_page and page_to_page become:
#define __pfn_to_page(pfn) (vmemmap + (pfn))
#define __page_to_pfn(page) ((page) - vmemmap)
By having a virtual mapping for the memmap we allow simple access without
wasting physical memory. As kernel memory is typically already mapped 1:1
this introduces no additional overhead. The virtual mapping must be big
enough to allow a struct page to be allocated and mapped for all valid
physical pages. This vill make a virtual memmap difficult to use on 32 bit
platforms that support 36 address bits.
However, if there is enough virtual space available and the arch already maps
its 1-1 kernel space using TLBs (f.e. true of IA64 and x86_64) then this
technique makes SPARSEMEM lookups even more efficient than CONFIG_FLATMEM.
FLATMEM needs to read the contents of the mem_map variable to get the start of
the memmap and then add the offset to the required entry. vmemmap is a
constant to which we can simply add the offset.
This patch has the potential to allow us to make SPARSMEM the default (and
even the only) option for most systems. It should be optimal on UP, SMP and
NUMA on most platforms. Then we may even be able to remove the other memory
models: FLATMEM, DISCONTIG etc.
The current aim is to bring a common virtually mapped mem_map to all
architectures. This should facilitate the removal of the bespoke
implementations from the architectures. This also brings performance
improvements for most architecture making sparsmem vmemmap the more desirable
memory model. The ultimate aim of this work is to expand sparsemem support to
encompass all the features of the other memory models. This could allow us to
drop support for and remove the other models in the longer term.
Below are some comparitive kernbench numbers for various architectures,
comparing default memory model against SPARSEMEM VMEMMAP. All but ia64 show
marginal improvement; we expect the ia64 figures to be sorted out when the
larger mapping support returns.
x86-64 non-NUMA
Base VMEMAP % change (-ve good)
User 85.07 84.84 -0.26
System 34.32 33.84 -1.39
Total 119.38 118.68 -0.59
ia64
Base VMEMAP % change (-ve good)
User 1016.41 1016.93 0.05
System 50.83 51.02 0.36
Total 1067.25 1067.95 0.07
x86-64 NUMA
Base VMEMAP % change (-ve good)
User 30.77 431.73 0.22
System 45.39 43.98 -3.11
Total 476.17 475.71 -0.10
ppc64
Base VMEMAP % change (-ve good)
User 488.77 488.35 -0.09
System 56.92 56.37 -0.97
Total 545.69 544.72 -0.18
Below are some AIM bencharks on IA64 and x86-64 (thank Bob). The seems
pretty much flat as you would expect.
ia64 results 2 cpu non-numa 4Gb SCSI disk
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" extreme Jun 1 07:17:24 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 98.9 100 58.9 1.3 1.6482
101 5547.1 95 106.0 79.4 0.9154
201 6377.7 95 183.4 158.3 0.5288
301 6932.2 95 252.7 237.3 0.3838
401 7075.8 93 329.8 316.7 0.2941
501 7235.6 94 403.0 396.2 0.2407
600 7387.5 94 472.7 475.0 0.2052
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" vmemmap Jun 1 09:59:04 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 99.1 100 58.8 1.2 1.6509
101 5480.9 95 107.2 79.2 0.9044
201 6490.3 95 180.2 157.8 0.5382
301 6886.6 94 254.4 236.8 0.3813
401 7078.2 94 329.7 316.0 0.2942
501 7250.3 95 402.2 395.4 0.2412
600 7399.1 94 471.9 473.9 0.2055
open power 710 2 cpu, 4 Gb, SCSI and configured physically
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" extreme May 29 15:42:53 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 25.7 100 226.3 4.3 0.4286
101 1096.0 97 536.4 199.8 0.1809
201 1236.4 96 946.1 389.1 0.1025
301 1280.5 96 1368.0 582.3 0.0709
401 1270.2 95 1837.4 771.0 0.0528
501 1251.4 96 2330.1 955.9 0.0416
601 1252.6 96 2792.4 1139.2 0.0347
701 1245.2 96 3276.5 1334.6 0.0296
918 1229.5 96 4345.4 1728.7 0.0223
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" vmemmap May 30 07:28:26 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 25.6 100 226.9 4.3 0.4275
101 1049.3 97 560.2 198.1 0.1731
201 1199.1 97 975.6 390.7 0.0994
301 1261.7 96 1388.5 591.5 0.0699
401 1256.1 96 1858.1 771.9 0.0522
501 1220.1 96 2389.7 955.3 0.0406
601 1224.6 96 2856.3 1133.4 0.0340
701 1252.0 96 3258.7 1314.1 0.0298
915 1232.8 96 4319.7 1704.0 0.0225
amd64 2 2-core, 4Gb and SATA
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" extreme Jun 2 03:59:48 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 13.0 100 446.4 2.1 0.2173
101 533.4 97 1102.0 110.2 0.0880
201 578.3 97 2022.8 220.8 0.0480
301 583.8 97 3000.6 332.3 0.0323
401 580.5 97 4020.1 442.2 0.0241
501 574.8 98 5072.8 558.8 0.0191
600 566.5 98 6163.8 671.0 0.0157
Benchmark Version Machine Run Date
AIM Multiuser Benchmark - Suite VII "1.1" vmemmap Jun 3 04:19:31 2007
Tasks Jobs/Min JTI Real CPU Jobs/sec/task
1 13.0 100 447.8 2.0 0.2166
101 536.5 97 1095.6 109.7 0.0885
201 567.7 97 2060.5 219.3 0.0471
301 582.1 96 3009.4 330.2 0.0322
401 578.2 96 4036.4 442.4 0.0240
501 585.1 98 4983.2 555.1 0.0195
600 565.5 98 6175.2 660.6 0.0157
This patch:
Fix some spelling errors.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This implements functionality to pass down or insert a barrier
in a queue, without having data attached to it. The ->prepare_flush_fn()
infrastructure from data barriers are reused to provide this
functionality.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
As bi_end_io is only called once when the reqeust is complete,
the 'size' argument is now redundant. Remove it.
Now there is no need for bio_endio to subtract the size completed
from bi_size. So don't do that either.
While we are at it, change bi_end_io to return void.
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Hide everything in blkdev.h with CONFIG_BLOCK isn't set, and fixup
the (few) files that fail to build because they were relying on blkdev.h
pulling in extra includes for them.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
find_lock_page increases page's usage count, we should decrease it
before return VM_FAULT_SIGBUS
Signed-off-by: Yan Zheng<yanzheng@21cn.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The test for VM_CAN_NONLINEAR always fails
Signed-off-by: Yan Zheng<yanzheng@21cn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All the current page_mkwrite() implementations also set the page dirty. Which
results in the set_page_dirty_balance() call to _not_ call balance, because the
page is already found dirty.
This allows us to dirty a _lot_ of pages without ever hitting
balance_dirty_pages(). Not good (tm).
Force a balance call if ->page_mkwrite() was successful.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When pinning and unpinning pagetables, we must protect them against
being used by other CPUs, lest they see the pagetable in an
intermediate read-only-but-not-pinned state.
When using split pte locks, doing this properly would require taking
all the pte locks for the pagetable while pinning, but this may overflow
the PREEMPT_BITS part of the preempt counter if the process has mapped
more than about 512M of memory.
However, failing to take the pte locks causes write-protect faults when
the pageout code is trying to clear the Access bit on a pte which is part
of a freshy created and still being pinned process after fork.
This is a short-term fix until the problem is solved properly.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Keir Fraser <keir@xensource.com>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Gurudas Pai reports kernel BUG at arch/i386/mm/highmem.c:15! below
sys_remap_file_pages, while running Oracle database test on x86 in 6GB
RAM: kunmap thinks we're in_interrupt because the preempt count has
wrapped.
That's because __do_fault expected to unmap page_table, but one of its
two callers do_nonlinear_fault already unmapped it: let do_linear_fault
unmap it first too, and then there's no need to pass the page_table arg
down.
Why have we been so slow to notice this? Probably through forgetting
that the mapping_cap_account_dirty test means that sys_remap_file_pages
nowadays only goes the full nonlinear vma route on a few memory-backed
filesystems like ramfs, tmpfs and hugetlbfs.
[ It also depends on CONFIG_HIGHPTE, so it becomes even harder to
trigger in practice. Many who have need of large memory have probably
migrated to x86-64..
Problem introduced by commit d0217ac04c
("mm: fault feedback #1") -- Linus ]
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: gurudas pai <gurudas.pai@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The virtual address space argument of clear_user_highpage is supposed to be
the virtual address where the page being cleared will eventually be mapped.
This allows architectures with virtually indexed caches a few clever
tricks. That sort of trick falls over in painful ways if the virtual
address argument is wrong.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch proposes fixes to the reference counting of memory policy in the
page allocation paths and in show_numa_map(). Extracted from my "Memory
Policy Cleanups and Enhancements" series as stand-alone.
Shared policy lookup [shmem] has always added a reference to the policy,
but this was never unrefed after page allocation or after formatting the
numa map data.
Default system policy should not require additional ref counting, nor
should the current task's task policy. However, show_numa_map() calls
get_vma_policy() to examine what may be [likely is] another task's policy.
The latter case needs protection against freeing of the policy.
This patch adds a reference count to a mempolicy returned by
get_vma_policy() when the policy is a vma policy or another task's
mempolicy. Again, shared policy is already reference counted on lookup. A
matching "unref" [__mpol_free()] is performed in alloc_page_vma() for
shared and vma policies, and in show_numa_map() for shared and another
task's mempolicy. We can call __mpol_free() directly, saving an admittedly
inexpensive inline NULL test, because we know we have a non-NULL policy.
Handling policy ref counts for hugepages is a bit trickier.
huge_zonelist() returns a zone list that might come from a shared or vma
'BIND policy. In this case, we should hold the reference until after the
huge page allocation in dequeue_hugepage(). The patch modifies
huge_zonelist() to return a pointer to the mempolicy if it needs to be
unref'd after allocation.
Kernel Build [16cpu, 32GB, ia64] - average of 10 runs:
w/o patch w/ refcount patch
Avg Std Devn Avg Std Devn
Real: 100.59 0.38 100.63 0.43
User: 1209.60 0.37 1209.91 0.31
System: 81.52 0.42 81.64 0.34
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This was posted on Aug 28 and fixes an issue that could cause troubles
when slab caches >=128k are created.
http://marc.info/?l=linux-mm&m=118798149918424&w=2
Currently we simply add the debug flags unconditional when checking for a
matching slab. This creates issues for sysfs processing when slabs exist
that are exempt from debugging due to their huge size or because only a
subset of slabs was selected for debugging.
We need to only add the flags if kmem_cache_open() would also add them.
Create a function to calculate the flags that would be set
if the cache would be opened and use that function to determine
the flags before looking for a compatible slab.
[akpm@linux-foundation.org: fixlets]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page migration currently does not check if the target of the move contains
nodes that that are invalid (if root attempts to migrate pages)
and may try to allocate from invalid nodes if these are specified
leading to oopses.
Return -EINVAL if an offline node is specified.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Do not BUG() if we cannot register a slab with sysfs. Just print an error.
The only consequence of not registering is that the slab cache is not
visible via /sys/slab. A BUG() may not be visible that early during boot
and we have had multiple issues here already.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In migration fallback path, write_page() or lock_page() will be called.
This causes sleep with holding rcu_read_lock().
For avoding that, just do rcu_lock if the page is Anon.(this is enough.)
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't try to free memory which we didn't allocate.
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The NUMA layer only supports NUMA policies for the highest zone. When
ZONE_MOVABLE is configured with kernelcore=, the the highest zone becomes
ZONE_MOVABLE. The result is that policies are only applied to allocations
like anonymous pages and page cache allocated from ZONE_MOVABLE when the
zone is used.
This patch applies policies to the two highest zones when the highest zone
is ZONE_MOVABLE. As ZONE_MOVABLE consists of pages from the highest "real"
zone, it's always functionally equivalent.
The patch has been tested on a variety of machines both NUMA and non-NUMA
covering x86, x86_64 and ppc64. No abnormal results were seen in
kernbench, tbench, dbench or hackbench. It passes regression tests from
the numactl package with and without kernelcore= once numactl tests are
patched to wait for vmstat counters to update.
akpm: this is the nasty hack to fix NUMA mempolicies in the presence of
ZONE_MOVABLE and kernelcore= in 2.6.23. Christoph says "For .24 either merge
the mobility or get the other solution that Mel is working on. That solution
would only use a single zonelist per node and filter on the fly. That may
help performance and also help to make memory policies work better."
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Tested-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Print a big fat warning and do what is necessary to continue if a node is
marked as up (meaning either node is online (upstream) or node has memory
(Andrew's tree)) but allocations from the node do not succeed.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
SLUB is using atomic_read() for variables declared atomic_long_t.
Switch to atomic_long_read().
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It seems a simple mistake was made when converting follow_hugetlb_page()
over to the VM_FAULT flags bitmasks (in "mm: fault feedback #2", commit
83c54070ee).
By using the wrong bitmask, hugetlb_fault() failures are not being
recognized. This results in an infinite loop whenever follow_hugetlb_page
is involved in a failed fault.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Skip calling cache_free_alien() when the platform is not numa capable.
This will avoid cache misses that happen while accessing slabp (which is
per page memory reference) to get nodeid. Instead use a global variable to
skip the call, which is mostly likely to be present in the cache.
This gives a 0.8% performance boost with the database oltp workload on a
quad-core SMP platform and by any means the number is not small :)
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The new exec code inserts an accounted vma into an mm struct which is not
current->mm. The existing memory check code has a hard coded assumption
that this does not happen as does the security code.
As the correct mm is known we pass the mm to the security method and the
helper function. A new security test is added for the case where we need
to pass the mm and the existing one is modified to pass current->mm to
avoid the need to change large amounts of code.
(Thanks to Tobias for fixing rejects and testing)
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Cc: James Morris <jmorris@redhat.com>
Cc: Tobias Diedrich <ranma+kernel@tdiedrich.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Lumpy reclaim works by selecting a lead page from the LRU list and then
selecting pages for reclaim from the order-aligned area of pages. In the
situation were all pages in that region are inactive and not referenced by any
process over time, it works well.
In the situation where there is even light load on the system, the pages may
not free quickly. Out of a area of 1024 pages, maybe only 950 of them are
freed when the allocation attempt occurs because lumpy reclaim returned early.
This patch alters the behaviour of direct reclaim for large contiguous
blocks.
The first attempt to call shrink_page_list() is asynchronous but if it fails,
the pages are submitted a second time and the calling process waits for the IO
to complete. This may stall allocators waiting for contiguous memory but that
should be expected behaviour for high-order users. It is preferable behaviour
to potentially queueing unnecessary areas for IO. Note that kswapd will not
stall in this fashion.
[apw@shadowen.org: update to version 2]
[apw@shadowen.org: update to version 3]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As pointed out by Mel when reclaim is applied at higher orders a significant
amount of IO may be started. As this takes finite time to drain reclaim will
consider more areas than ultimatly needed to satisfy the request. This leads
to more reclaim than strictly required and reduced success rates.
I was able to confirm Mel's test results on systems locally. These show that
even under light load the success rates drop off far more than expected.
Testing with a modified version of his patch (which follows) I was able to
allocate almost all of ZONE_MOVABLE with a near idle system. I ran 5 test
passes sequentially following system boot (the system has 29 hugepages in
ZONE_MOVABLE):
2.6.23-rc1 11 8 6 7 7
sync_lumpy 28 28 29 29 26
These show that although hugely better than the near 0% success normally
expected we can only allocate about a 1/4 of the zone. Using synchronous
reclaim for these allocations we get close to 100% as expected.
I have also run our standard high order tests and these show no regressions in
allocation success rates at rest, and some significant improvements under
load.
This patch:
We are transitioning pages from active to inactive in clear_active_flags,
those need counting as PGDEACTIVATE vm events.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Booting SPARSEMEM on NUMA systems trips a BUG in page_alloc.c:
Initializing HighMem for node 0 (00038000:00100000)
Initializing HighMem for node 1 (00100000:001ffe00)
------------[ cut here ]------------
kernel BUG at /home/apw/git/linux-2.6/mm/page_alloc.c:456!
[...]
This occurs because the section to node id mapping is not being
setup correctly during init under SPARSEMEM_STATIC, leading to an
attempt to free pages from all nodes into the zones on node 0.
When the zone_table[] was removed in the following commit, a new
section to node mapping table was introduced:
commit 89689ae7f9
[PATCH] Get rid of zone_table[]
That conversion inadvertantly only initialised the node mapping in
SPARSEMEM_EXTREME. Ensure we initialise the node mapping in
SPARSEMEM_STATIC.
[akpm@linux-foundation.org: make the stubs static inline]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
BLOCK: Hide the contents of linux/bio.h if CONFIG_BLOCK=n
sysace: HDIO_GETGEO has it's own method for ages
drivers/block/cpqarray.c: better error handling and kmalloc + memset conversion to k[cz]alloc
drivers/block/cciss.c: kmalloc + memset conversion to kzalloc
Clean up duplicate includes in drivers/block/
Fix remap handling by blktrace
[PATCH] remove mm/filemap.c:file_send_actor()
Minor docbook error since argument name in comment doesn't match function
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The dynamic dma kmalloc creation can run into trouble if a
GFP_ATOMIC allocation is the first one performed for a certain size
of dma kmalloc slab.
- Move the adding of the slab to sysfs into a workqueue
(sysfs does GFP_KERNEL allocations)
- Do not call kmem_cache_destroy() (uses slub_lock)
- Only acquire the slub_lock once and--if we cannot wait--do a trylock.
This introduces a slight risk of the first kmalloc(x, GFP_DMA|GFP_ATOMIC)
for a range of sizes failing due to another process holding the slub_lock.
However, we only need to acquire the spinlock once in order to establish
each power of two DMA kmalloc cache. The possible conflict is with the
slub_lock taken during slab management actions (create / remove slab cache).
It is rather typical that a driver will first fill its buffers using
GFP_KERNEL allocations which will wait until the slub_lock can be acquired.
Drivers will also create its slab caches first outside of an atomic
context before starting to use atomic kmalloc from an interrupt context.
If there are any failures then they will occur early after boot or when
loading of multiple drivers concurrently. Drivers can already accomodate
failures of GFP_ATOMIC for other reasons. Retries will then create the slab.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
The MAX_PARTIAL checks were supposed to be an optimization. However, slab
shrinking is a manually triggered process either through running slabinfo
or by the kernel calling kmem_cache_shrink.
If one really wants to shrink a slab then all operations should be done
regardless of the size of the partial list. This also fixes an issue that
could surface if the number of partial slabs was initially above MAX_PARTIAL
in kmem_cache_shrink and later drops below MAX_PARTIAL through the
elimination of empty slabs on the partial list (rare). In that case a few
slabs may be left off the partial list (and only be put back when they
are empty).
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Fix kernel-doc warning:
Warning(linux-2.6.23-rc1-mm1//mm/filemap.c:864): No description found for parameter 'ra'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In badness(), the automatic variable 'points' is unsigned long. Print it
as such.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
out_of_memory() may be called when an allocation is failing and the direct
reclaim is not making any progress. This does not take into account the
requested order of the allocation. If the request if for an order larger
than PAGE_ALLOC_COSTLY_ORDER, it is reasonable to fail the allocation
because the kernel makes no guarantees about those allocations succeeding.
This false OOM situation can occur if a user is trying to grow the hugepage
pool in a script like;
#!/bin/bash
REQUIRED=$1
echo 1 > /proc/sys/vm/hugepages_treat_as_movable
echo $REQUIRED > /proc/sys/vm/nr_hugepages
ACTUAL=`cat /proc/sys/vm/nr_hugepages`
while [ $REQUIRED -ne $ACTUAL ]; do
echo Huge page pool at $ACTUAL growing to $REQUIRED
echo $REQUIRED > /proc/sys/vm/nr_hugepages
ACTUAL=`cat /proc/sys/vm/nr_hugepages`
sleep 1
done
This is a reasonable scenario when ZONE_MOVABLE is in use but triggers OOM
easily on 2.6.23-rc1. This patch will fail an allocation for an order above
PAGE_ALLOC_COSTLY_ORDER instead of killing processes and retrying.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We ClearSlabDebug() before the last SlabDebug() check. Clear it later.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Ingo noticed that the SLUB code does include the lock debugging free
check.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Introduce CONFIG_SUSPEND representing the ability to enter system sleep
states, such as the ACPI S3 state, and allow the user to choose SUSPEND
and HIBERNATION independently of each other.
Make HOTPLUG_CPU be selected automatically if SUSPEND or HIBERNATION has
been chosen and the kernel is intended for SMP systems.
Also, introduce CONFIG_PM_SLEEP which is automatically selected if
CONFIG_SUSPEND or CONFIG_HIBERNATION is set and use it to select the
code needed for both suspend and hibernation.
The top-level power management headers and the ACPI code related to
suspend and hibernation are modified to use the new definitions (the
changes in drivers/acpi/sleep/main.c are, mostly, moving code to reduce
the number of ifdefs).
There are many other files in which CONFIG_PM can be replaced with
CONFIG_PM_SLEEP or even with CONFIG_SUSPEND, but they can be updated in
the future.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace CONFIG_SOFTWARE_SUSPEND with CONFIG_HIBERNATION to avoid
confusion (among other things, with CONFIG_SUSPEND introduced in the
next patch).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With the introduction of kernelcore=, a configurable zone is created on
request. In some cases, this value will be small enough that some nodes
contain only ZONE_MOVABLE. On some NUMA configurations when this occurs,
arch-independent zone-sizing will get the size of the memory holes within
the node incorrect. The value of present_pages goes negative and the boot
fails.
This patch fixes the bug in the calculation of the size of the hole. The
test case is to boot test a NUMA machine with a low value of kernelcore=
before and after the patch is applied. While this bug exists in early
kernel it cannot be triggered in practice.
This patch has been boot-tested on a variety machines with and without
kernelcore= set.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
release_pages() in mm/swap.c changes page_count() to be 0 without removing
PageLRU flag...
This means isolate_lru_page() can see a page, PageLRU() &&
page_count(page)==0.. This is BUG. (get_page() will be called against
count=0 page.)
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In usual, migrate_pages(page,,) is called with holding mm->sem by system call.
(mm here is a mm_struct which maps the migration target page.)
This semaphore helps avoiding some race conditions.
But, if we want to migrate a page by some kernel codes, we have to avoid
some races. This patch adds check code for following race condition.
1. A page which page->mapping==NULL can be target of migration. Then, we have
to check page->mapping before calling try_to_unmap().
2. anon_vma can be freed while page is unmapped, but page->mapping remains as
it was. We drop page->mapcount to be 0. Then we cannot trust page->mapping.
So, use rcu_read_lock() to prevent anon_vma pointed by page->mapping from
being freed during migration.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'request-queue-t' of git://git.kernel.dk/linux-2.6-block:
[BLOCK] Add request_queue_t and mark it deprecated
[BLOCK] Get rid of request_queue_t typedef
Use the correct local variable when calling into the page allocator. Local
`flags' can have __GFP_ZERO set, which causes us to pass __GFP_ZERO into the
page allocator, possibly from illegal contexts. The page allocator will later
do prep_zero_page()->kmap_atomic(..., KM_USER0) from irq contexts and will
then go BUG.
Cc: Mike Galbraith <efault@gmx.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
dequeue_huge_page() has a serious memory leak upon hugetlb page
allocation. The for loop continues on allocating hugetlb pages out of
all allowable zone, where this function is supposedly only dequeue one
and only one pages.
Fixed it by breaking out of the for loop once a hugetlb page is found.
Signed-off-by: Ken Chen <kenchen@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some of the code has been gradually transitioned to using the proper
struct request_queue, but there's lots left. So do a full sweet of
the kernel and get rid of this typedef and replace its uses with
the proper type.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Fix following warning:
WARNING: vmlinux.o(.text+0x188ea): Section mismatch: reference to .init.text:__alloc_bootmem_core (between 'alloc_bootmem_high_node' and 'get_gate_vma')
alloc_bootmem_high_node() is only used from __init scope so declare it __init.
And in addition declare the weak variant __init too.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The version of SLOB in -mm always scans its free list from the beginning,
which results in small allocations and free segments clustering at the
beginning of the list over time. This causes the average search to scan
over a large stretch at the beginning on each allocation.
By starting each page search where the last one left off, we evenly
distribute the allocations and greatly shorten the average search.
Without this patch, kernel compiles on a 1.5G machine take a large amount
of system time for list scanning. With this patch, compiles are within a
few seconds of performance of a SLAB kernel with no notable change in
system time.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that arch/powerpc/platforms/cell/spufs/fault.c is always built in
the kernel there is no need to export handle_mm_fault anymore.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Trying to survive an allmodconfig on a nommu platform results in many
screen lengths of module unhappiness. Many of the mmap related things that
binfmt_flat hooks in to are never exported despite being global, and there
are also missing definitions for vmalloc_32_user() and vm_insert_page().
I've implemented vmalloc_32_user() trying to stick as close to the
mm/vmalloc.c implementation as possible, though we don't have any need for
VM_USERMAP, so groveling for the VMA can be skipped. vm_insert_page() has
been stubbed for now in order to keep the build happy.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zone_movable_pfn is presently marked as __initdata and referenced from
adjust_zone_range_for_zone_movable(), which in turn is referenced by
zone_spanned_pages_in_node(). Both of these are __meminit annotated. When
memory hotplug is enabled, this will oops on a hot-add, due to
zone_movable_pfn having been freed.
__meminitdata annotation gives the desired behaviour.
This will only impact platforms that enable both memory hotplug
and ARCH_POPULATES_NODE_MAP.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Slab destructors were no longer supported after Christoph's
c59def9f22 change. They've been
BUGs for both slab and slub, and slob never supported them
either.
This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
The slab and slob allocators already did this right, but slub would call
"get_object_page()" on the magic ZERO_SIZE_PTR, with all kinds of nasty
end results.
Noted by Ingo Molnar.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I suspect Christoph tested his code only in the NUMA configuration, for
the combination of SLAB+non-NUMA the zero-sized kmalloc's would not work.
Of course, this would only trigger in configurations where those zero-
sized allocations happen (not very common), so that may explain why it
wasn't more widely noticed.
Seen by by Andi Kleen under qemu, and there seems to be a report by
Michael Tsirkin on it too.
Cc: Andi Kleen <ak@suse.de>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: Michael S. Tsirkin <mst@dev.mellanox.co.il>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lguest does some fairly lowlevel things to support a host, which
normal modules don't need:
math_state_restore:
When the guest triggers a Device Not Available fault, we need
to be able to restore the FPU
__put_task_struct:
We need to hold a reference to another task for inter-guest
I/O, and put_task_struct() is an inline function which calls
__put_task_struct.
access_process_vm:
We need to access another task for inter-guest I/O.
map_vm_area & __get_vm_area:
We need to map the switcher shim (ie. monitor) at 0xFFC01000.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page-writeback accounting is presently performed in the page-flags macros.
This is inconsistent and a bit ugly and makes it awkward to implement
per-backing_dev under-writeback page accounting.
So move this accounting down to the callsite(s).
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use appropriate accessor function to set compound page destructor
function.
Cc: William Irwin <wli@holomorphy.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The fix to that race in alloc_fresh_huge_page() which could give an illegal
node ID did not need nid_lock at all: the fix was to replace static int nid
by static int prev_nid and do the work on local int nid. nid_lock did make
sure that racers strictly roundrobin the nodes, but that's not something we
need to enforce strictly. Kill nid_lock.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've noticed lots of failures of vmalloc_32 on machines where it
shouldn't have failed unless it was doing an atomic operation.
Looking closely, I noticed that:
#if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
#define GFP_VMALLOC32 GFP_DMA32
#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
#define GFP_VMALLOC32 GFP_DMA
#else
#define GFP_VMALLOC32 GFP_KERNEL
#endif
Which seems to be incorrect, it should always -or- in the DMA flags
on top of GFP_KERNEL, thus this patch.
This fixes frequent errors launchin X with the nouveau DRM for example.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Work around a possible bug in the FRV compiler.
What appears to be happening is that gcc resolves the
__builtin_constant_p() in kmalloc() to true, but then fails to reduce the
therefore constant conditions in the if-statements it guards to constant
results.
When compiling with -O2 or -Os, one single spurious error crops up in
cpuup_callback() in mm/slab.c. This can be avoided by making the memsize
variable const.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/hugetlb.c: In function `dequeue_huge_page':
mm/hugetlb.c:72: warning: 'nid' might be used uninitialized in this function
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <hermes@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
the old mm into the new mm.
We create the new mm before the binfmt code runs, and place the new stack at
the very top of the address space. Once the binfmt code runs and figures out
where the stack should be, we move it downwards.
It is a bit peculiar in that we have one task with two mm's, one of which is
inactive.
[a.p.zijlstra@chello.nl: limit stack size]
Signed-off-by: Ollie Wild <aaw@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-arch@vger.kernel.org>
Cc: Hugh Dickins <hugh@veritas.com>
[bunk@stusta.de: unexport bprm_mm_init]
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename some file_ra_state variables and remove some accessors.
It results in much simpler code.
Kudos to Rusty!
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Split ondemand readahead interface into two functions. I think this makes it
a little clearer for non-readahead experts (like Rusty).
Internally they both call ondemand_readahead(), but the page argument is
changed to an obvious boolean flag.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Share the same page flag bit for PG_readahead and PG_reclaim.
One is used only on file reads, another is only for emergency writes. One
is used mostly for fresh/young pages, another is for old pages.
Combinations of possible interactions are:
a) clear PG_reclaim => implicit clear of PG_readahead
it will delay an asynchronous readahead into a synchronous one
it actually does _good_ for readahead:
the pages will be reclaimed soon, it's readahead thrashing!
in this case, synchronous readahead makes more sense.
b) clear PG_readahead => implicit clear of PG_reclaim
one(and only one) page will not be reclaimed in time
it can be avoided by checking PageWriteback(page) in readahead first
c) set PG_reclaim => implicit set of PG_readahead
will confuse readahead and make it restart the size rampup process
it's a trivial problem, and can mostly be avoided by checking
PageWriteback(page) first in readahead
d) set PG_readahead => implicit set of PG_reclaim
PG_readahead will never be set on already cached pages.
PG_reclaim will always be cleared on dirtying a page.
so not a problem.
In summary,
a) we get better behavior
b,d) possible interactions can be avoided
c) racy condition exists that might affect readahead, but the chance
is _really_ low, and the hurt on readahead is trivial.
Compound pages also use PG_reclaim, but for now they do not interact with
reclaim/readahead code.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the old readahead algorithm.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert filemap reads to use on-demand readahead.
The new call scheme is to
- call readahead on non-cached page
- call readahead on look-ahead page
- update prev_index when finished with the read request
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a minimal readahead algorithm that aims to replace the current one.
It is more flexible and reliable, while maintaining almost the same behavior
and performance. Also it is full integrated with adaptive readahead.
It is designed to be called on demand:
- on a missing page, to do synchronous readahead
- on a lookahead page, to do asynchronous readahead
In this way it eliminated the awkward workarounds for cache hit/miss,
readahead thrashing, retried read, and unaligned read. It also adopts the
data structure introduced by adaptive readahead, parameterizes readahead
pipelining with `lookahead_index', and reduces the current/ahead windows to
one single window.
HEURISTICS
The logic deals with four cases:
- sequential-next
found a consistent readahead window, so push it forward
- random
standalone small read, so read as is
- sequential-first
create a new readahead window for a sequential/oversize request
- lookahead-clueless
hit a lookahead page not associated with the readahead window,
so create a new readahead window and ramp it up
In each case, three parameters are determined:
- readahead index: where the next readahead begins
- readahead size: how much to readahead
- lookahead size: when to do the next readahead (for pipelining)
BEHAVIORS
The old behaviors are maximally preserved for trivial sequential/random reads.
Notable changes are:
- It no longer imposes strict sequential checks.
It might help some interleaved cases, and clustered random reads.
It does introduce risks of a random lookahead hit triggering an
unexpected readahead. But in general it is more likely to do good
than to do evil.
- Interleaved reads are supported in a minimal way.
Their chances of being detected and proper handled are still low.
- Readahead thrashings are better handled.
The current readahead leads to tiny average I/O sizes, because it
never turn back for the thrashed pages. They have to be fault in
by do_generic_mapping_read() one by one. Whereas the on-demand
readahead will redo readahead for them.
OVERHEADS
The new code reduced the overheads of
- excessively calling the readahead routine on small sized reads
(the current readahead code insists on seeing all requests)
- doing a lot of pointless page-cache lookups for small cached files
(the current readahead only turns itself off after 256 cache hits,
unfortunately most files are < 1MB, so never see that chance)
That accounts for speedup of
- 0.3% on 1-page sequential reads on sparse file
- 1.2% on 1-page cache hot sequential reads
- 3.2% on 256-page cache hot sequential reads
- 1.3% on cache hot `tar /lib`
However, it does introduce one extra page-cache lookup per cache miss, which
impacts random reads slightly. That's 1% overheads for 1-page random reads on
sparse file.
PERFORMANCE
The basic benchmark setup is
- 2.6.20 kernel with on-demand readahead
- 1MB max readahead size
- 2.9GHz Intel Core 2 CPU
- 2GB memory
- 160G/8M Hitachi SATA II 7200 RPM disk
The benchmarks show that
- it maintains the same performance for trivial sequential/random reads
- sysbench/OLTP performance on MySQL gains up to 8%
- performance on readahead thrashing gains up to 3 times
iozone throughput (KB/s): roughly the same
==========================================
iozone -c -t1 -s 4096m -r 64k
2.6.20 on-demand gain
first run
" Initial write " 61437.27 64521.53 +5.0%
" Rewrite " 47893.02 48335.20 +0.9%
" Read " 62111.84 62141.49 +0.0%
" Re-read " 62242.66 62193.17 -0.1%
" Reverse Read " 50031.46 49989.79 -0.1%
" Stride read " 8657.61 8652.81 -0.1%
" Random read " 13914.28 13898.23 -0.1%
" Mixed workload " 19069.27 19033.32 -0.2%
" Random write " 14849.80 14104.38 -5.0%
" Pwrite " 62955.30 65701.57 +4.4%
" Pread " 62209.99 62256.26 +0.1%
second run
" Initial write " 60810.31 66258.69 +9.0%
" Rewrite " 49373.89 57833.66 +17.1%
" Read " 62059.39 62251.28 +0.3%
" Re-read " 62264.32 62256.82 -0.0%
" Reverse Read " 49970.96 50565.72 +1.2%
" Stride read " 8654.81 8638.45 -0.2%
" Random read " 13901.44 13949.91 +0.3%
" Mixed workload " 19041.32 19092.04 +0.3%
" Random write " 14019.99 14161.72 +1.0%
" Pwrite " 64121.67 68224.17 +6.4%
" Pread " 62225.08 62274.28 +0.1%
In summary, writes are unstable, reads are pretty close on average:
access pattern 2.6.20 on-demand gain
Read 62085.61 62196.38 +0.2%
Re-read 62253.49 62224.99 -0.0%
Reverse Read 50001.21 50277.75 +0.6%
Stride read 8656.21 8645.63 -0.1%
Random read 13907.86 13924.07 +0.1%
Mixed workload 19055.29 19062.68 +0.0%
Pread 62217.53 62265.27 +0.1%
aio-stress: roughly the same
============================
aio-stress -l -s4096 -r128 -t1 -o1 knoppix511-dvd-cn.iso
aio-stress -l -s4096 -r128 -t1 -o3 knoppix511-dvd-cn.iso
2.6.20 on-demand delta
sequential 92.57s 92.54s -0.0%
random 311.87s 312.15s +0.1%
sysbench fileio: roughly the same
=================================
sysbench --test=fileio --file-io-mode=async --file-test-mode=rndrw \
--file-total-size=4G --file-block-size=64K \
--num-threads=001 --max-requests=10000 --max-time=900 run
threads 2.6.20 on-demand delta
first run
1 59.1974s 59.2262s +0.0%
2 58.0575s 58.2269s +0.3%
4 48.0545s 47.1164s -2.0%
8 41.0684s 41.2229s +0.4%
16 35.8817s 36.4448s +1.6%
32 32.6614s 32.8240s +0.5%
64 23.7601s 24.1481s +1.6%
128 24.3719s 23.8225s -2.3%
256 23.2366s 22.0488s -5.1%
second run
1 59.6720s 59.5671s -0.2%
8 41.5158s 41.9541s +1.1%
64 25.0200s 23.9634s -4.2%
256 22.5491s 20.9486s -7.1%
Note that the numbers are not very stable because of the writes.
The overall performance is close when we sum all seconds up:
sum all up 495.046s 491.514s -0.7%
sysbench oltp (trans/sec): up to 8% gain
========================================
sysbench --test=oltp --oltp-table-size=10000000 --oltp-read-only \
--mysql-socket=/var/run/mysqld/mysqld.sock \
--mysql-user=root --mysql-password=readahead \
--num-threads=064 --max-requests=10000 --max-time=900 run
10000-transactions run
threads 2.6.20 on-demand gain
1 62.81 64.56 +2.8%
2 67.97 70.93 +4.4%
4 81.81 85.87 +5.0%
8 94.60 97.89 +3.5%
16 99.07 104.68 +5.7%
32 95.93 104.28 +8.7%
64 96.48 103.68 +7.5%
5000-transactions run
1 48.21 48.65 +0.9%
8 68.60 70.19 +2.3%
64 70.57 74.72 +5.9%
2000-transactions run
1 37.57 38.04 +1.3%
2 38.43 38.99 +1.5%
4 45.39 46.45 +2.3%
8 51.64 52.36 +1.4%
16 54.39 55.18 +1.5%
32 52.13 54.49 +4.5%
64 54.13 54.61 +0.9%
That's interesting results. Some investigations show that
- MySQL is accessing the db file non-uniformly: some parts are
more hot than others
- It is mostly doing 4-page random reads, and sometimes doing two
reads in a row, the latter one triggers a 16-page readahead.
- The on-demand readahead leaves many lookahead pages (flagged
PG_readahead) there. Many of them will be hit, and trigger
more readahead pages. Which might save more seeks.
- Naturally, the readahead windows tend to lie in hot areas,
and the lookahead pages in hot areas is more likely to be hit.
- The more overall read density, the more possible gain.
That also explains the adaptive readahead tricks for clustered random reads.
readahead thrashing: 3 times better
===================================
We boot kernel with "mem=128m single", and start a 100KB/s stream on every
second, until reaching 200 streams.
max throughput min avg I/O size
2.6.20: 5MB/s 16KB
on-demand: 15MB/s 140KB
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extend struct file_ra_state to support the on-demand readahead logic. Also
define some helpers for it.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Define two convenient macros for read-ahead:
- MAX_RA_PAGES: rounded down counterpart of VM_MAX_READAHEAD
- MIN_RA_PAGES: rounded _up_ counterpart of VM_MIN_READAHEAD
Note that the rounded up MIN_RA_PAGES will work flawlessly with _large_
page sizes like 64k.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add look-ahead support to __do_page_cache_readahead().
It works by
- mark the Nth backwards page with PG_readahead,
(which instructs the page's first reader to invoke readahead)
- and only do the marking for newly allocated pages.
(to prevent blindly doing readahead on already cached pages)
Look-ahead is a technique to achieve I/O pipelining:
While the application is working through a chunk of cached pages, the kernel
reads-ahead the next chunk of pages _before_ time of need. It effectively
hides low level I/O latencies to high level applications.
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a new page flag: PG_readahead.
It acts as a look-ahead mark, which tells the page reader: Hey, it's time to
invoke the read-ahead logic. For the sake of I/O pipelining, don't wait until
it runs out of cached pages!
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_mkclean() doesn't re-protect ptes for non-linear mappings, so a later
re-dirty through such a mapping will not generate a fault, PG_dirty will
not reflect the dirty state and the dirty count will be skewed. This
implies that msync() is also currently broken for nonlinear mappings.
The easiest solution is to emulate remap_file_pages on non-linear mappings
with simple mmap() for non ram-backed filesystems. Applications continue
to work (albeit slower), as long as the number of remappings remain below
the maximum vma count.
However all currently known real uses of non-linear mappings are for ram
backed filesystems, which this patch doesn't affect.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix msync data loss and (less importantly) dirty page accounting
inaccuracies due to the race remaining in clear_page_dirty_for_io().
The deleted comment explains what the race was, and the added comments
explain how it is fixed.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch completes Linus's wish that the fault return codes be made into
bit flags, which I agree makes everything nicer. This requires requires
all handle_mm_fault callers to be modified (possibly the modifications
should go further and do things like fault accounting in handle_mm_fault --
however that would be for another patch).
[akpm@linux-foundation.org: fix alpha build]
[akpm@linux-foundation.org: fix s390 build]
[akpm@linux-foundation.org: fix sparc build]
[akpm@linux-foundation.org: fix sparc64 build]
[akpm@linux-foundation.org: fix ia64 build]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[ Still apparently needs some ARM and PPC loving - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change ->fault prototype. We now return an int, which contains
VM_FAULT_xxx code in the low byte, and FAULT_RET_xxx code in the next byte.
FAULT_RET_ code tells the VM whether a page was found, whether it has been
locked, and potentially other things. This is not quite the way he wanted
it yet, but that's changed in the next patch (which requires changes to
arch code).
This means we no longer set VM_CAN_INVALIDATE in the vma in order to say
that a page is locked which requires filemap_nopage to go away (because we
can no longer remain backward compatible without that flag), but we were
going to do that anyway.
struct fault_data is renamed to struct vm_fault as Linus asked. address
is now a void __user * that we should firmly encourage drivers not to use
without really good reason.
The page is now returned via a page pointer in the vm_fault struct.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__do_fault() was calling ->page_mkwrite() with the page lock held, which
violates the locking rules for that callback. Release and retake the page
lock around the callback to avoid deadlocking file systems which manually
take it.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes
the virtual address -> file offset differently from linear mappings.
->populate is a layering violation because the filesystem/pagecache code
should need to know anything about the virtual memory mapping. The hitch here
is that the ->nopage handler didn't pass down enough information (ie. pgoff).
But it is more logical to pass pgoff rather than have the ->nopage function
calculate it itself anyway (because that's a similar layering violation).
Having the populate handler install the pte itself is likewise a nasty thing
to be doing.
This patch introduces a new fault handler that replaces ->nopage and
->populate and (later) ->nopfn. Most of the old mechanism is still in place
so there is a lot of duplication and nice cleanups that can be removed if
everyone switches over.
The rationale for doing this in the first place is that nonlinear mappings are
subject to the pagefault vs invalidate/truncate race too, and it seemed stupid
to duplicate the synchronisation logic rather than just consolidate the two.
After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in
pagecache. Seems like a fringe functionality anyway.
NOPAGE_REFAULT is removed. This should be implemented with ->fault, and no
users have hit mainline yet.
[akpm@linux-foundation.org: cleanup]
[randy.dunlap@oracle.com: doc. fixes for readahead]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix the race between invalidate_inode_pages and do_no_page.
Andrea Arcangeli identified a subtle race between invalidation of pages from
pagecache with userspace mappings, and do_no_page.
The issue is that invalidation has to shoot down all mappings to the page,
before it can be discarded from the pagecache. Between shooting down ptes to
a particular page, and actually dropping the struct page from the pagecache,
do_no_page from any process might fault on that page and establish a new
mapping to the page just before it gets discarded from the pagecache.
The most common case where such invalidation is used is in file truncation.
This case was catered for by doing a sort of open-coded seqlock between the
file's i_size, and its truncate_count.
Truncation will decrease i_size, then increment truncate_count before
unmapping userspace pages; do_no_page will read truncate_count, then find the
page if it is within i_size, and then check truncate_count under the page
table lock and back out and retry if it had subsequently been changed (ptl
will serialise against unmapping, and ensure a potentially updated
truncate_count is actually visible).
Complexity and documentation issues aside, the locking protocol fails in the
case where we would like to invalidate pagecache inside i_size. do_no_page
can come in anytime and filemap_nopage is not aware of the invalidation in
progress (as it is when it is outside i_size). The end result is that
dangling (->mapping == NULL) pages that appear to be from a particular file
may be mapped into userspace with nonsense data. Valid mappings to the same
place will see a different page.
Andrea implemented two working fixes, one using a real seqlock, another using
a page->flags bit. He also proposed using the page lock in do_no_page, but
that was initially considered too heavyweight. However, it is not a global or
per-file lock, and the page cacheline is modified in do_no_page to increment
_count and _mapcount anyway, so a further modification should not be a large
performance hit. Scalability is not an issue.
This patch implements this latter approach. ->nopage implementations return
with the page locked if it is possible for their underlying file to be
invalidated (in that case, they must set a special vm_flags bit to indicate
so). do_no_page only unlocks the page after setting up the mapping
completely. invalidation is excluded because it holds the page lock during
invalidation of each page (and ensures that the page is not mapped while
holding the lock).
This also allows significant simplifications in do_no_page, because we have
the page locked in the right place in the pagecache from the start.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allocate/release a chunk of vmalloc address space:
alloc_vm_area reserves a chunk of address space, and makes sure all
the pagetables are constructed for that address range - but no pages.
free_vm_area releases the address space range.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: "Jan Beulich" <JBeulich@novell.com>
Cc: "Andi Kleen" <ak@muc.de>
Add a kstrndup function, modelled on strndup. Like strndup this
returns a string copied into its own allocated memory, but it copies
no more than the specified number of bytes from the source.
Remove private strndup() from irda code.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@mandriva.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Panagiotis Issaris <takis@issaris.org>
Cc: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Our original NFSv4 delegation policy was to give out a read delegation on any
open when it was possible to.
Since the lifetime of a delegation isn't limited to that of an open, a client
may quite reasonably hang on to a delegation as long as it has the inode
cached. This becomes an obvious problem the first time a client's inode cache
approaches the size of the server's total memory.
Our first quick solution was to add a hard-coded limit. This patch makes a
mild incremental improvement by varying that limit according to the server's
total memory size, allowing at most 4 delegations per megabyte of RAM.
My quick back-of-the-envelope calculation finds that in the worst case (where
every delegation is for a different inode), a delegation could take about
1.5K, which would make the worst case usage about 6% of memory. The new limit
works out to be about the same as the old on a 1-gig server.
[akpm@linux-foundation.org: Don't needlessly bloat vmlinux]
[akpm@linux-foundation.org: Make it right for highmem machines]
Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
currently the export_operation structure and helpers related to it are in
fs.h. fs.h is already far too large and there are very few places needing the
export bits, so split them off into a separate header.
[akpm@linux-foundation.org: fix cifs build]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer. This is nonsense and error-prone. Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.
This patch increments KSYM_NAME_LEN by one and updates code accordingly.
* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
is fixed.
* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
MODULE_NAME_LEN was treated as if it didn't include space for the
trailing '\0'. Fix it.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The bounce buffer logic is included on systems that do not need it. If a
system does not have zones like ZONE_DMA and ZONE_HIGHMEM that can lead to
the use of bounce buffers then there is no need to reserve memory pools etc
etc. This is true f.e. for SGI Altix.
Also nicifies the Makefile and gets rid of the tricky "and" there.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves. This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.
It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.
The patch causes all kernel threads to be nonfreezable by default (ie. to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE. It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear. Additionally, it updates documentation to
describe the freezing of tasks more accurately.
[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is a bug to set a page dirty if it is not uptodate unless it has
buffers. If the page has buffers, then the page may be dirty (some buffers
dirty) but not uptodate (some buffers not uptodate). The exception to this
rule is if the set_page_dirty caller is racing with truncate or invalidate.
A buffer can not be set dirty if it is not uptodate.
If either of these situations occurs, it indicates there could be some data
loss problem. Some of these warnings could be a harmless one where the
page or buffer is set uptodate immediately after it is dirtied, however we
should fix those up, and enforce this ordering.
Bring the order of operations for truncate into line with those of
invalidate. This will prevent a page from being able to go !uptodate while
we're holding the tree_lock, which is probably a good thing anyway.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently cannot disable CONFIG_SLUB_DEBUG for CONFIG_NUMA. Now that
embedded systems start to use NUMA we may need this.
Put an #ifdef around places where NUMA only code uses fields only valid
for CONFIG_SLUB_DEBUG.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sysfs can do a gazillion things when called. Make sure that we do not call
any sysfs functions while holding the slub_lock.
Just protect the essentials:
1. The list of all slab caches
2. The kmalloc_dma array
3. The ref counters of the slabs.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The objects per slab increase with the current patches in mm since we allow up
to order 3 allocs by default. More patches in mm actually allow to use 2M or
higher sized slabs. For slab validation we need per object bitmaps in order
to check a slab. We end up with up to 64k objects per slab resulting in a
potential requirement of 8K stack space. That does not look good.
Allocate the bit arrays via kmalloc.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmalloc_node() and kmem_cache_alloc_node() were not available in a zeroing
variant in the past. But with __GFP_ZERO it is possible now to do zeroing
while allocating.
Use __GFP_ZERO to remove the explicit clearing of memory via memset whereever
we can.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It becomes now easy to support the zeroing allocs with generic inline
functions in slab.h. Provide inline definitions to allow the continued use of
kzalloc, kmem_cache_zalloc etc but remove other definitions of zeroing
functions from the slab allocators and util.c.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can get to the length of the object through the kmem_cache_structure. The
additional parameter does no good and causes the compiler to generate bad
code.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Do proper spacing and we only need to do this in steps of 8.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is no need to caculate the dma slab size ourselves. We can simply
lookup the size of the corresponding non dma slab.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmalloc_index is a long series of comparisons. The attempt to replace
kmalloc_index with something more efficient like ilog2 failed due to compiler
issues with constant folding on gcc 3.3 / powerpc.
kmalloc_index()'es long list of comparisons works fine for constant folding
since all the comparisons are optimized away. However, SLUB also uses
kmalloc_index to determine the slab to use for the __kmalloc_xxx functions.
This leads to a large set of comparisons in get_slab().
The patch here allows to get rid of that list of comparisons in get_slab():
1. If the requested size is larger than 192 then we can simply use
fls to determine the slab index since all larger slabs are
of the power of two type.
2. If the requested size is smaller then we cannot use fls since there
are non power of two caches to be considered. However, the sizes are
in a managable range. So we divide the size by 8. Then we have only
24 possibilities left and then we simply look up the kmalloc index
in a table.
Code size of slub.o decreases by more than 200 bytes through this patch.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We modify the kmalloc_cache_dma[] array without proper locking. Do the proper
locking and undo the dma cache creation if another processor has already
created it.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The rarely used dma functionality in get_slab() makes the function too
complex. The compiler begins to spill variables from the working set onto the
stack. The created function is only used in extremely rare cases so make sure
that the compiler does not decide on its own to merge it back into get_slab().
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add #ifdefs around data structures only needed if debugging is compiled into
SLUB.
Add inlines to small functions to reduce code size.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A kernel convention for many allocators is that if __GFP_ZERO is passed to an
allocator then the allocated memory should be zeroed.
This is currently not supported by the slab allocators. The inconsistency
makes it difficult to implement in derived allocators such as in the uncached
allocator and the pool allocators.
In addition the support zeroed allocations in the slab allocators does not
have a consistent API. There are no zeroing allocator functions for NUMA node
placement (kmalloc_node, kmem_cache_alloc_node). The zeroing allocations are
only provided for default allocs (kzalloc, kmem_cache_zalloc_node).
__GFP_ZERO will make zeroing universally available and does not require any
addititional functions.
So add the necessary logic to all slab allocators to support __GFP_ZERO.
The code is added to the hot path. The gfp flags are on the stack and so the
cacheline is readily available for checking if we want a zeroed object.
Zeroing while allocating is now a frequent operation and we seem to be
gradually approaching a 1-1 parity between zeroing and not zeroing allocs.
The current tree has 3476 uses of kmalloc vs 2731 uses of kzalloc.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Define ZERO_OR_NULL_PTR macro to be able to remove the checks from the
allocators. Move ZERO_SIZE_PTR related stuff into slab.h.
Make ZERO_SIZE_PTR work for all slab allocators and get rid of the
WARN_ON_ONCE(size == 0) that is still remaining in SLAB.
Make slub return NULL like the other allocators if a too large memory segment
is requested via __kmalloc.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The size of a kmalloc object is readily available via ksize(). ksize is
provided by all allocators and thus we can implement krealloc in a generic
way.
Implement krealloc in mm/util.c and drop slab specific implementations of
krealloc.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The function we are calling to initialize object debug state during early NUMA
bootstrap sets up an inactive object giving it the wrong redzone signature.
The bootstrap nodes are active objects and should have active redzone
signatures.
Currently slab validation complains and reverts the object to active state.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently SLUB has no provision to deal with too high page orders that may
be specified on the kernel boot line. If an order higher than 6 (on a 4k
platform) is generated then we will BUG() because slabs get more than 65535
objects.
Add some logic that decreases order for slabs that have too many objects.
This allow booting with slab sizes up to MAX_ORDER.
For example
slub_min_order=10
will boot with a default slab size of 4M and reduce slab sizes for small
object sizes to lower orders if the number of objects becomes too big.
Large slab sizes like that allow a concentration of objects of the same
slab cache under as few as possible TLB entries and thus potentially
reduces TLB pressure.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently have to do an GFP_ATOMIC allocation because the list_lock is
already taken when we first allocate memory for tracking allocation
information. It would be better if we could avoid atomic allocations.
Allocate a size of the tracking table that is usually sufficient (one page)
before we take the list lock. We will then only do the atomic allocation
if we need to resize the table to become larger than a page (mostly only
needed under large NUMA because of the tracking of cpus and nodes otherwise
the table stays small).
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use list_for_each_entry() instead of list_for_each().
Get rid of for_all_slabs(). It had only one user. So fold it into the
callback. This also gets rid of cpu_slab_flush.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Changes the error reporting format to loosely follow lockdep.
If data corruption is detected then we generate the following lines:
============================================
BUG <slab-cache>: <problem>
--------------------------------------------
INFO: <more information> [possibly multiple times]
<object dump>
FIX <slab-cache>: <remedial action>
This also adds some more intelligence to the data corruption detection. Its
now capable of figuring out the start and end.
Add a comment on how to configure SLUB so that a production system may
continue to operate even though occasional slab corruption occur through
a misbehaving kernel component. See "Emergency operations" in
Documentation/vm/slub.txt.
[akpm@linux-foundation.org: build fix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I can never remember what the function to register to receive VM pressure
is called. I have to trace down from __alloc_pages() to find it.
It's called "set_shrinker()", and it needs Your Help.
1) Don't hide struct shrinker. It contains no magic.
2) Don't allocate "struct shrinker". It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Chinner <dgc@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we are out of memory of a suitable size we enter reclaim. The current
reclaim algorithm targets pages in LRU order, which is great for fairness at
order-0 but highly unsuitable if you desire pages at higher orders. To get
pages of higher order we must shoot down a very high proportion of memory;
>95% in a lot of cases.
This patch set adds a lumpy reclaim algorithm to the allocator. It targets
groups of pages at the specified order anchored at the end of the active and
inactive lists. This encourages groups of pages at the requested orders to
move from active to inactive, and active to free lists. This behaviour is
only triggered out of direct reclaim when higher order pages have been
requested.
This patch set is particularly effective when utilised with an
anti-fragmentation scheme which groups pages of similar reclaimability
together.
This patch set is based on Peter Zijlstra's lumpy reclaim V2 patch which forms
the foundation. Credit to Mel Gorman for sanitity checking.
Mel said:
The patches have an application with hugepage pool resizing.
When lumpy-reclaim is used used with ZONE_MOVABLE, the hugepages pool can
be resized with greater reliability. Testing on a desktop machine with 2GB
of RAM showed that growing the hugepage pool with ZONE_MOVABLE on it's own
was very slow as the success rate was quite low. Without lumpy-reclaim,
each attempt to grow the pool by 100 pages would yield 1 or 2 hugepages.
With lumpy-reclaim, getting 40 to 70 hugepages on each attempt was typical.
[akpm@osdl.org: ia64 pfn_to_nid fixes and loop cleanup]
[bunk@stusta.de: static declarations for internal functions]
[a.p.zijlstra@chello.nl: initial lumpy V2 implementation]
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds a new parameter for sizing ZONE_MOVABLE called
movablecore=. While kernelcore= is used to specify the minimum amount of
memory that must be available for all allocation types, movablecore= is
used to specify the minimum amount of memory that is used for migratable
allocations. The amount of memory used for migratable allocations
determines how large the huge page pool could be dynamically resized to at
runtime for example.
How movablecore is actually handled is that the total number of pages in
the system is calculated and a value is set for kernelcore that is
kernelcore == totalpages - movablecore
Both kernelcore= and movablecore= can be safely specified at the same time.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds the kernelcore= parameter for x86.
Once all patches are applied, a new command-line parameter exist and a new
sysctl. This patch adds the necessary documentation.
From: Yasunori Goto <y-goto@jp.fujitsu.com>
When "kernelcore" boot option is specified, kernel can't boot up on ia64
because of an infinite loop. In addition, the parsing code can be handled
in an architecture-independent manner.
This patch uses common code to handle the kernelcore= parameter. It is
only available to architectures that support arch-independent zone-sizing
(i.e. define CONFIG_ARCH_POPULATES_NODE_MAP). Other architectures will
ignore the boot parameter.
[bunk@stusta.de: make cmdline_parse_kernelcore() static]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Huge pages are not movable so are not allocated from ZONE_MOVABLE. However,
as ZONE_MOVABLE will always have pages that can be migrated or reclaimed, it
can be used to satisfy hugepage allocations even when the system has been
running a long time. This allows an administrator to resize the hugepage pool
at runtime depending on the size of ZONE_MOVABLE.
This patch adds a new sysctl called hugepages_treat_as_movable. When a
non-zero value is written to it, future allocations for the huge page pool
will use ZONE_MOVABLE. Despite huge pages being non-movable, we do not
introduce additional external fragmentation of note as huge pages are always
the largest contiguous block we care about.
[akpm@linux-foundation.org: various fixes]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nick Piggin