The check in pool_page_reusable (page_to_nid(page) == pool->p.nid) is
not valid if page_pool was configured with pool->p.nid = NUMA_NO_NODE.
The goal of the NUMA changes in commit d5394610b1 ("page_pool: Don't
recycle non-reusable pages"), were to have RX-pages that belongs to the
same NUMA node as the CPU processing RX-packet during softirq/NAPI. As
illustrated by the performance measurements.
This patch moves the NAPI checks out of fast-path, and at the same time
solves the NUMA_NO_NODE issue.
First realize that alloc_pages_node() with pool->p.nid = NUMA_NO_NODE
will lookup current CPU nid (Numa ID) via numa_mem_id(), which is used
as the the preferred nid. It is only in rare situations, where
e.g. NUMA zone runs dry, that page gets doesn't get allocated from
preferred nid. The page_pool API allows drivers to control the nid
themselves via controlling pool->p.nid.
This patch moves the NAPI check to when alloc cache is refilled, via
dequeuing/consuming pages from the ptr_ring. Thus, we can allow placing
pages from remote NUMA into the ptr_ring, as the dequeue/consume step
will check the NUMA node. All current drivers using page_pool will
alloc/refill RX-ring from same CPU running softirq/NAPI process.
Drivers that control the nid explicitly, also use page_pool_update_nid
when changing nid runtime. To speed up transision to new nid the alloc
cache is now flushed on nid changes. This force pages to come from
ptr_ring, which does the appropate nid check.
For the NUMA_NO_NODE case, when a NIC IRQ is moved to another NUMA
node, we accept that transitioning the alloc cache doesn't happen
immediately. The preferred nid change runtime via consulting
numa_mem_id() based on the CPU processing RX-packets.
Notice, to avoid stressing the page buddy allocator and avoid doing too
much work under softirq with preempt disabled, the NUMA check at
ptr_ring dequeue will break the refill cycle, when detecting a NUMA
mismatch. This will cause a slower transition, but its done on purpose.
Fixes: d5394610b1 ("page_pool: Don't recycle non-reusable pages")
Reported-by: Li RongQing <lirongqing@baidu.com>
Reported-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Introduce the following parameters in order to add the possibility to sync
DMA memory for device before putting allocated pages in the page_pool
caches:
- PP_FLAG_DMA_SYNC_DEV: if set in page_pool_params flags, all pages that
the driver gets from page_pool will be DMA-synced-for-device according
to the length provided by the device driver. Please note DMA-sync-for-CPU
is still device driver responsibility
- offset: DMA address offset where the DMA engine starts copying rx data
- max_len: maximum DMA memory size page_pool is allowed to flush. This
is currently used in __page_pool_alloc_pages_slow routine when pages
are allocated from page allocator
These parameters are supposed to be set by device drivers.
This optimization reduces the length of the DMA-sync-for-device.
The optimization is valid because pages are initially
DMA-synced-for-device as defined via max_len. At RX time, the driver
will perform a DMA-sync-for-CPU on the memory for the packet length.
What is important is the memory occupied by packet payload, because
this is the area CPU is allowed to read and modify. As we don't track
cache-lines written into by the CPU, simply use the packet payload length
as dma_sync_size at page_pool recycle time. This also take into account
any tail-extend.
Tested-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
A page is NOT reusable when at least one of the following is true:
1) allocated when system was under some pressure. (page_is_pfmemalloc)
2) belongs to a different NUMA node than pool->p.nid.
To update pool->p.nid users should call page_pool_update_nid().
Holding on to such pages in the pool will hurt the consumer performance
when the pool migrates to a different numa node.
Performance testing:
XDP drop/tx rate and TCP single/multi stream, on mlx5 driver
while migrating rx ring irq from close to far numa:
mlx5 internal page cache was locally disabled to get pure page pool
results.
CPU: Intel(R) Xeon(R) CPU E5-2603 v4 @ 1.70GHz
NIC: Mellanox Technologies MT27700 Family [ConnectX-4] (100G)
XDP Drop/TX single core:
NUMA | XDP | Before | After
---------------------------------------
Close | Drop | 11 Mpps | 10.9 Mpps
Far | Drop | 4.4 Mpps | 5.8 Mpps
Close | TX | 6.5 Mpps | 6.5 Mpps
Far | TX | 3.5 Mpps | 4 Mpps
Improvement is about 30% drop packet rate, 15% tx packet rate for numa
far test.
No degradation for numa close tests.
TCP single/multi cpu/stream:
NUMA | #cpu | Before | After
--------------------------------------
Close | 1 | 18 Gbps | 18 Gbps
Far | 1 | 15 Gbps | 18 Gbps
Close | 12 | 80 Gbps | 80 Gbps
Far | 12 | 68 Gbps | 80 Gbps
In all test cases we see improvement for the far numa case, and no
impact on the close numa case.
The impact of adding a check per page is very negligible, and shows no
performance degradation whatsoever, also functionality wise it seems more
correct and more robust for page pool to verify when pages should be
recycled, since page pool can't guarantee where pages are coming from.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add page_pool_update_nid() to be called by page pool consumers when they
detect numa node changes.
It will update the page pool nid value to start allocating from the new
effective numa node.
This is to mitigate page pool allocating pages from a wrong numa node,
where the pool was originally allocated, and holding on to pages that
belong to a different numa node, which causes performance degradation.
For pages that are already being consumed and could be returned to the
pool by the consumer, in next patch we will add a check per page to avoid
recycling them back to the pool and return them to the page allocator.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When Jonathan change the page_pool to become responsible to its
own shutdown via deferred work queue, then the disconnect_cnt
counter was removed from xdp memory model tracepoint.
This patch change the page_pool_inflight tracepoint name to
page_pool_release, because it reflects the new responsability
better. And it reintroduces a counter that reflect the number of
times page_pool_release have been tried.
The counter is also used by the code, to only empty the alloc
cache once. With a stuck work queue running every second and
counter being 64-bit, it will overrun in approx 584 billion
years. For comparison, Earth lifetime expectancy is 7.5 billion
years, before the Sun will engulf, and destroy, the Earth.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The page pool keeps track of the number of pages in flight, and
it isn't safe to remove the pool until all pages are returned.
Disallow removing the pool until all pages are back, so the pool
is always available for page producers.
Make the page pool responsible for its own delayed destruction
instead of relying on XDP, so the page pool can be used without
the xdp memory model.
When all pages are returned, free the pool and notify xdp if the
pool is registered with the xdp memory system. Have the callback
perform a table walk since some drivers (cpsw) may share the pool
among multiple xdp_rxq_info.
Note that the increment of pages_state_release_cnt may result in
inflight == 0, resulting in the pool being released.
Fixes: d956a048cd ("xdp: force mem allocator removal and periodic warning")
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
__page_pool_get_cached() will return NULL when the ring is
empty, even if there are pages present in the lookaside cache.
It is also possible to refill the cache, and then return a
NULL page.
Restructure the logic so eliminate both cases.
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Remove variable initializations in functions that
are followed by assignments before use
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jesper recently removed page_pool_destroy() (from driver invocation)
and moved shutdown and free of page_pool into xdp_rxq_info_unreg(),
in-order to handle in-flight packets/pages. This created an asymmetry
in drivers create/destroy pairs.
This patch reintroduce page_pool_destroy and add page_pool user
refcnt. This serves the purpose to simplify drivers error handling as
driver now drivers always calls page_pool_destroy() and don't need to
track if xdp_rxq_info_reg_mem_model() was unsuccessful.
This could be used for a special cases where a single RX-queue (with a
single page_pool) provides packets for two net_device'es, and thus
needs to register the same page_pool twice with two xdp_rxq_info
structures.
This patch is primarily to ease API usage for drivers. The recently
merged netsec driver, actually have a bug in this area, which is
solved by this API change.
This patch is a modified version of Ivan Khoronzhuk's original patch.
Link: https://lore.kernel.org/netdev/20190625175948.24771-2-ivan.khoronzhuk@linaro.org/
Fixes: 5c67bf0ec4 ("net: netsec: Use page_pool API")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
For DMA mapping use-case the page_pool keeps a pointer
to the struct device, which is used in DMA map/unmap calls.
For our in-flight handling, we also need to make sure that
the struct device have not disappeared. This is assured
via using get_device/put_device API.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reported-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
The xdp tracepoints for mem id disconnect don't carry information about, why
it was not safe_to_remove. The tracepoint page_pool:page_pool_inflight in
this patch can be used for extract this info for further debugging.
This patchset also adds tracepoint for the pages_state_* release/hold
transitions, including a pointer to the page. This can be used for stats
about in-flight pages, or used to debug page leakage via keeping track of
page pointer and combining this with kprobe for __put_page().
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If bugs exists or are introduced later e.g. by drivers misusing the API,
then we want to warn about the issue, such that developer notice. This patch
will generate a bit of noise in form of periodic pr_warn every 30 seconds.
It is not nice to have this stall warning running forever. Thus, this patch
will (after 120 attempts) force disconnect the mem id (from the rhashtable)
and free the page_pool object. This will cause fallback to the put_page() as
before, which only potentially leak DMA-mappings, if objects are really
stuck for this long. In that unlikely case, a WARN_ONCE should show us the
call stack.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch is needed before we can allow drivers to use page_pool for
DMA-mappings. Today with page_pool and XDP return API, it is possible to
remove the page_pool object (from rhashtable), while there are still
in-flight packet-pages. This is safely handled via RCU and failed lookups in
__xdp_return() fallback to call put_page(), when page_pool object is gone.
In-case page is still DMA mapped, this will result in page note getting
correctly DMA unmapped.
To solve this, the page_pool is extended with tracking in-flight pages. And
XDP disconnect system queries page_pool and waits, via workqueue, for all
in-flight pages to be returned.
To avoid killing performance when tracking in-flight pages, the implement
use two (unsigned) counters, that in placed on different cache-lines, and
can be used to deduct in-flight packets. This is done by mapping the
unsigned "sequence" counters onto signed Two's complement arithmetic
operations. This is e.g. used by kernel's time_after macros, described in
kernel commit 1ba3aab303 and 5a581b367b, and also explained in RFC1982.
The trick is these two incrementing counters only need to be read and
compared, when checking if it's safe to free the page_pool structure. Which
will only happen when driver have disconnected RX/alloc side. Thus, on a
non-fast-path.
It is chosen that page_pool tracking is also enabled for the non-DMA
use-case, as this can be used for statistics later.
After this patch, using page_pool requires more strict resource "release",
e.g. via page_pool_release_page() that was introduced in this patchset, and
previous patches implement/fix this more strict requirement.
Drivers no-longer call page_pool_destroy(). Drivers already call
xdp_rxq_info_unreg() which call xdp_rxq_info_unreg_mem_model(), which will
attempt to disconnect the mem id, and if attempt fails schedule the
disconnect for later via delayed workqueue.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
In case driver fails to register the page_pool with XDP return API (via
xdp_rxq_info_reg_mem_model()), then the driver can free the page_pool
resources more directly than calling page_pool_destroy(), which does a
unnecessarily RCU free procedure.
This patch is preparing for removing page_pool_destroy(), from driver
invocation.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
On a previous patch dma addr was stored in 'struct page'.
Use that to unmap DMA addresses used by network drivers
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
As pointed out by Alexander Duyck, the DMA mapping done in page_pool needs
to use the DMA attribute DMA_ATTR_SKIP_CPU_SYNC.
As the principle behind page_pool keeping the pages mapped is that the
driver takes over the DMA-sync steps.
Reported-by: Alexander Duyck <alexander.duyck@gmail.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
As pointed out by David Miller the current page_pool implementation
stores dma_addr_t in page->private.
This won't work on 32-bit platforms with 64-bit DMA addresses since the
page->private is an unsigned long and the dma_addr_t a u64.
A previous patch is adding dma_addr_t on struct page to accommodate this.
This patch adapts the page_pool related functions to use the newly added
struct for storing and retrieving DMA addresses from network drivers.
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Need a fast page recycle mechanism for ndo_xdp_xmit API for returning
pages on DMA-TX completion time, which have good cross CPU
performance, given DMA-TX completion time can happen on a remote CPU.
Refurbish my page_pool code, that was presented[1] at MM-summit 2016.
Adapted page_pool code to not depend the page allocator and
integration into struct page. The DMA mapping feature is kept,
even-though it will not be activated/used in this patchset.
[1] http://people.netfilter.org/hawk/presentations/MM-summit2016/generic_page_pool_mm_summit2016.pdf
V2: Adjustments requested by Tariq
- Changed page_pool_create return codes, don't return NULL, only
ERR_PTR, as this simplifies err handling in drivers.
V4: many small improvements and cleanups
- Add DOC comment section, that can be used by kernel-doc
- Improve fallback mode, to work better with refcnt based recycling
e.g. remove a WARN as pointed out by Tariq
e.g. quicker fallback if ptr_ring is empty.
V5: Fixed SPDX license as pointed out by Alexei
V6: Adjustments requested by Eric Dumazet
- Adjust ____cacheline_aligned_in_smp usage/placement
- Move rcu_head in struct page_pool
- Free pages quicker on destroy, minimize resources delayed an RCU period
- Remove code for forward/backward compat ABI interface
V8: Issues found by kbuild test robot
- Address sparse should be static warnings
- Only compile+link when a driver use/select page_pool,
mlx5 selects CONFIG_PAGE_POOL, although its first used in two patches
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jesper Dangaard Brouer