Commit Graph

7 Commits

Author SHA1 Message Date
Linus Torvalds f412f2c60b Merge branch 'for-linus' of git://git.kernel.dk/linux-block
Pull second round of block driver updates from Jens Axboe:
 "As mentioned in the original pull request, the bcache bits were pulled
  because of their dependency on the immutable bio vecs.  Kent re-did
  this part and resubmitted it, so here's the 2nd round of (mostly)
  driver updates for 3.13.  It contains:

 - The bcache work from Kent.

 - Conversion of virtio-blk to blk-mq.  This removes the bio and request
   path, and substitutes with the blk-mq path instead.  The end result
   almost 200 deleted lines.  Patch is acked by Asias and Christoph, who
   both did a bunch of testing.

 - A removal of bootmem.h include from Grygorii Strashko, part of a
   larger series of his killing the dependency on that header file.

 - Removal of __cpuinit from blk-mq from Paul Gortmaker"

* 'for-linus' of git://git.kernel.dk/linux-block: (56 commits)
  virtio_blk: blk-mq support
  blk-mq: remove newly added instances of __cpuinit
  bcache: defensively handle format strings
  bcache: Bypass torture test
  bcache: Delete some slower inline asm
  bcache: Use ida for bcache block dev minor
  bcache: Fix sysfs splat on shutdown with flash only devs
  bcache: Better full stripe scanning
  bcache: Have btree_split() insert into parent directly
  bcache: Move spinlock into struct time_stats
  bcache: Kill sequential_merge option
  bcache: Kill bch_next_recurse_key()
  bcache: Avoid deadlocking in garbage collection
  bcache: Incremental gc
  bcache: Add make_btree_freeing_key()
  bcache: Add btree_node_write_sync()
  bcache: PRECEDING_KEY()
  bcache: bch_(btree|extent)_ptr_invalid()
  bcache: Don't bother with bucket refcount for btree node allocations
  bcache: Debug code improvements
  ...
2013-11-15 16:33:41 -08:00
Christoph Hellwig 0a06ff068f kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS
We've switched over every architecture that supports SMP to it, so
remove the new useless config variable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-15 09:32:22 +09:00
Paul Gortmaker f618ef7c47 blk-mq: remove newly added instances of __cpuinit
The new blk-mq code added new instances of __cpuinit usage.
We removed this a couple versions ago; we now want to remove
the compat no-op stubs.  Introducing new users is not what
we want to see at this point in time, as it will break once
the stubs are gone.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-11-14 08:26:02 -07:00
Shaohua Li 92f399c72a blk-mq: mq plug list breakage
We switched to plug mq_list for mq, but some code are still using old list.

Signed-off-by: Shaohua Li <shli@fusionio.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-29 12:01:03 -06:00
Christoph Hellwig 3228f48be2 blk-mq: fix for flush deadlock
The flush state machine takes in a struct request, which then is
submitted multiple times to the underling driver.  The old block code
requeses the same request for each of those, so it does not have an
issue with tapping into the request pool.  The new one on the other hand
allocates a new request for each of the actualy steps of the flush
sequence. If have already allocated all of the tags for IO, we will
fail allocating the flush request.

Set aside a reserved request just for flushes.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-28 13:33:58 -06:00
Christoph Hellwig 280d45f6c3 blk-mq: add blk_mq_stop_hw_queues
Add a helper to iterate over all hw queues and stop them.  This is useful
for driver that implement PM suspend functionality.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Modified to just call blk_mq_stop_hw_queue() by Jens.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-25 14:45:58 +01:00
Jens Axboe 320ae51fee blk-mq: new multi-queue block IO queueing mechanism
Linux currently has two models for block devices:

- The classic request_fn based approach, where drivers use struct
  request units for IO. The block layer provides various helper
  functionalities to let drivers share code, things like tag
  management, timeout handling, queueing, etc.

- The "stacked" approach, where a driver squeezes in between the
  block layer and IO submitter. Since this bypasses the IO stack,
  driver generally have to manage everything themselves.

With drivers being written for new high IOPS devices, the classic
request_fn based driver doesn't work well enough. The design dates
back to when both SMP and high IOPS was rare. It has problems with
scaling to bigger machines, and runs into scaling issues even on
smaller machines when you have IOPS in the hundreds of thousands
per device.

The stacked approach is then most often selected as the model
for the driver. But this means that everybody has to re-invent
everything, and along with that we get all the problems again
that the shared approach solved.

This commit introduces blk-mq, block multi queue support. The
design is centered around per-cpu queues for queueing IO, which
then funnel down into x number of hardware submission queues.
We might have a 1:1 mapping between the two, or it might be
an N:M mapping. That all depends on what the hardware supports.

blk-mq provides various helper functions, which include:

- Scalable support for request tagging. Most devices need to
  be able to uniquely identify a request both in the driver and
  to the hardware. The tagging uses per-cpu caches for freed
  tags, to enable cache hot reuse.

- Timeout handling without tracking request on a per-device
  basis. Basically the driver should be able to get a notification,
  if a request happens to fail.

- Optional support for non 1:1 mappings between issue and
  submission queues. blk-mq can redirect IO completions to the
  desired location.

- Support for per-request payloads. Drivers almost always need
  to associate a request structure with some driver private
  command structure. Drivers can tell blk-mq this at init time,
  and then any request handed to the driver will have the
  required size of memory associated with it.

- Support for merging of IO, and plugging. The stacked model
  gets neither of these. Even for high IOPS devices, merging
  sequential IO reduces per-command overhead and thus
  increases bandwidth.

For now, this is provided as a potential 3rd queueing model, with
the hope being that, as it matures, it can replace both the classic
and stacked model. That would get us back to having just 1 real
model for block devices, leaving the stacked approach to dm/md
devices (as it was originally intended).

Contributions in this patch from the following people:

Shaohua Li <shli@fusionio.com>
Alexander Gordeev <agordeev@redhat.com>
Christoph Hellwig <hch@infradead.org>
Mike Christie <michaelc@cs.wisc.edu>
Matias Bjorling <m@bjorling.me>
Jeff Moyer <jmoyer@redhat.com>

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-10-25 11:56:00 +01:00