On 10/01/2025 14.06, Yunsheng Lin wrote:
This patchset fix a possible time window problem for page_pool and
the dma API misuse problem as mentioned in [1], and try to avoid the
overhead of the fixing using some optimization.
From the below performance data, the overhead is not so obvious
due to performance variations for time_bench_page_pool01_fast_path()
and time_bench_page_pool02_ptr_ring, and there is about 20ns overhead
for time_bench_page_pool03_slow() for fixing the bug.
My benchmarking on x86_64 CPUs looks significantly different.
- CPU: Intel(R) Xeon(R) CPU E5-1650 v4 @ 3.60GHz
Benchmark (bench_page_pool_simple) results from before and after patchset:
| Test name | Cycles | | |Nanosec | | | % |
| (tasklet_*)| Before | After |diff| Before | After | diff | change |
|------------+--------+-------+----+--------+--------+-------+--------|
| fast_path | 19 | 24 | 5| 5.399 | 6.928 | 1.529 | 28.3 |
| ptr_ring | 54 | 79 | 25| 15.090 | 21.976 | 6.886 | 45.6 |
| slow | 238 | 299 | 61| 66.134 | 83.298 |17.164 | 26.0 |
#+TBLFM: $4=$3-$2::$7=$6-$5::$8=(($7/$5)*100);%.1f
My above testing show a clear performance regressions across three
different page_pool operating modes.
Data also available in:
-
https://github.com/xdp-project/xdp-project/blob/main/areas/mem/page_pool07_bench_DMA_fix.org
Raw data below
Before this patchset:
[ 157.186644] bench_page_pool_simple: Loaded
[ 157.475084] time_bench: Type:for_loop Per elem: 1 cycles(tsc) 0.284
ns (step:0) - (measurement period time:0.284327440 sec
time_interval:284327440) - (invoke count:1000000000 tsc_interval:1023590451)
[ 162.262752] time_bench: Type:atomic_inc Per elem: 17 cycles(tsc)
4.769 ns (step:0) - (measurement period time:4.769757001 sec
time_interval:4769757001) - (invoke count:1000000000
tsc_interval:17171776113)
[ 163.324091] time_bench: Type:lock Per elem: 37 cycles(tsc) 10.431 ns
(step:0) - (measurement period time:1.043182161 sec
time_interval:1043182161) - (invoke count:100000000 tsc_interval:3755514465)
[ 163.341702] bench_page_pool_simple:
time_bench_page_pool01_fast_path(): Cannot use page_pool fast-path
[ 163.922466] time_bench: Type:no-softirq-page_pool01 Per elem: 20
cycles(tsc) 5.713 ns (step:0) - (measurement period time:0.571357387 sec
time_interval:571357387) - (invoke count:100000000 tsc_interval:2056911063)
[ 163.941429] bench_page_pool_simple:
time_bench_page_pool02_ptr_ring(): Cannot use page_pool fast-path
[ 165.506796] time_bench: Type:no-softirq-page_pool02 Per elem: 56
cycles(tsc) 15.560 ns (step:0) - (measurement period time:1.556080558
sec time_interval:1556080558) - (invoke count:100000000
tsc_interval:5601960921)
[ 165.525978] bench_page_pool_simple: time_bench_page_pool03_slow():
Cannot use page_pool fast-path
[ 171.811289] time_bench: Type:no-softirq-page_pool03 Per elem: 225
cycles(tsc) 62.763 ns (step:0) - (measurement period time:6.276301531
sec time_interval:6276301531) - (invoke count:100000000
tsc_interval:22594974468)
[ 171.830646] bench_page_pool_simple: pp_tasklet_handler():
in_serving_softirq fast-path
[ 171.838561] bench_page_pool_simple:
time_bench_page_pool01_fast_path(): in_serving_softirq fast-path
[ 172.387597] time_bench: Type:tasklet_page_pool01_fast_path Per elem:
19 cycles(tsc) 5.399 ns (step:0) - (measurement period time:0.539904228
sec time_interval:539904228) - (invoke count:100000000
tsc_interval:1943679246)
[ 172.407130] bench_page_pool_simple:
time_bench_page_pool02_ptr_ring(): in_serving_softirq fast-path
[ 173.925266] time_bench: Type:tasklet_page_pool02_ptr_ring Per elem:
54 cycles(tsc) 15.090 ns (step:0) - (measurement period time:1.509075496
sec time_interval:1509075496) - (invoke count:100000000
tsc_interval:5432740575)
[ 173.944878] bench_page_pool_simple: time_bench_page_pool03_slow():
in_serving_softirq fast-path
[ 180.567094] time_bench: Type:tasklet_page_pool03_slow Per elem: 238
cycles(tsc) 66.134 ns (step:0) - (measurement period time:6.613430605
sec time_interval:6613430605) - (invoke count:100000000
tsc_interval:23808654870)
After this patchset:
[ 860.519918] bench_page_pool_simple: Loaded
[ 860.781605] time_bench: Type:for_loop Per elem: 0 cycles(tsc) 0.257
ns (step:0) - (measurement period time:0.257573336 sec
time_interval:257573336) - (invoke count:1000000000 tsc_interval:927275355)
[ 865.613893] time_bench: Type:atomic_inc Per elem: 17 cycles(tsc)
4.814 ns (step:0) - (measurement period time:4.814593429 sec
time_interval:4814593429) - (invoke count:1000000000
tsc_interval:17332768494)
[ 866.708420] time_bench: Type:lock Per elem: 38 cycles(tsc) 10.763 ns
(step:0) - (measurement period time:1.076362960 sec
time_interval:1076362960) - (invoke count:100000000 tsc_interval:3874955595)
[ 866.726118] bench_page_pool_simple:
time_bench_page_pool01_fast_path(): Cannot use page_pool fast-path
[ 867.423572] time_bench: Type:no-softirq-page_pool01 Per elem: 24
cycles(tsc) 6.880 ns (step:0) - (measurement period time:0.688069107 sec
time_interval:688069107) - (invoke count:100000000 tsc_interval:2477080260)
[ 867.442517] bench_page_pool_simple:
time_bench_page_pool02_ptr_ring(): Cannot use page_pool fast-path
[ 869.436286] time_bench: Type:no-softirq-page_pool02 Per elem: 71
cycles(tsc) 19.844 ns (step:0) - (measurement period time:1.984451929
sec time_interval:1984451929) - (invoke count:100000000
tsc_interval:7144120329)
[ 869.455492] bench_page_pool_simple: time_bench_page_pool03_slow():
Cannot use page_pool fast-path
[ 877.071437] time_bench: Type:no-softirq-page_pool03 Per elem: 273
cycles(tsc) 76.069 ns (step:0) - (measurement period time:7.606911291
sec time_interval:7606911291) - (invoke count:100000000
tsc_interval:27385252251)
[ 877.090762] bench_page_pool_simple: pp_tasklet_handler():
in_serving_softirq fast-path
[ 877.098683] bench_page_pool_simple:
time_bench_page_pool01_fast_path(): in_serving_softirq fast-path
[ 877.800696] time_bench: Type:tasklet_page_pool01_fast_path Per elem:
24 cycles(tsc) 6.928 ns (step:0) - (measurement period time:0.692852876
sec time_interval:692852876) - (invoke count:100000000
tsc_interval:2494303293)
[ 877.820224] bench_page_pool_simple:
time_bench_page_pool02_ptr_ring(): in_serving_softirq fast-path
[ 880.026911] time_bench: Type:tasklet_page_pool02_ptr_ring Per elem:
79 cycles(tsc) 21.976 ns (step:0) - (measurement period time:2.197615122
sec time_interval:2197615122) - (invoke count:100000000
tsc_interval:7911521190)
[ 880.046528] bench_page_pool_simple: time_bench_page_pool03_slow():
in_serving_softirq fast-path
[ 888.385235] time_bench: Type:tasklet_page_pool03_slow Per elem: 299
cycles(tsc) 83.298 ns (step:0) - (measurement period time:8.329893717
sec time_interval:8329893717) - (invoke count:100000000
tsc_interval:29988024696)
Before this patchset:
root@(none)$ insmod bench_page_pool_simple.ko
[ 323.367627] bench_page_pool_simple: Loaded
[ 323.448747] time_bench: Type:for_loop Per elem: 0 cycles(tsc) 0.769 ns (step:0) - (measurement period time:0.076997150 sec time_interval:76997150) - (invoke count:100000000 tsc_interval:7699707)
[ 324.812884] time_bench: Type:atomic_inc Per elem: 1 cycles(tsc) 13.468 ns (step:0) - (measurement period time:1.346855130 sec time_interval:1346855130) - (invoke count:100000000 tsc_interval:134685507)
[ 324.980875] time_bench: Type:lock Per elem: 1 cycles(tsc) 15.010 ns (step:0) - (measurement period time:0.150101270 sec time_interval:150101270) - (invoke count:10000000 tsc_interval:15010120)
[ 325.652195] time_bench: Type:rcu Per elem: 0 cycles(tsc) 6.542 ns (step:0) - (measurement period time:0.654213000 sec time_interval:654213000) - (invoke count:100000000 tsc_interval:65421294)
[ 325.669215] bench_page_pool_simple: time_bench_page_pool01_fast_path(): Cannot use page_pool fast-path
[ 325.974848] time_bench: Type:no-softirq-page_pool01 Per elem: 2 cycles(tsc) 29.633 ns (step:0) - (measurement period time:0.296338200 sec time_interval:296338200) - (invoke count:10000000 tsc_interval:29633814)
[ 325.993517] bench_page_pool_simple: time_bench_page_pool02_ptr_ring(): Cannot use page_pool fast-path
[ 326.576636] time_bench: Type:no-softirq-page_pool02 Per elem: 5 cycles(tsc) 57.391 ns (step:0) - (measurement period time:0.573911820 sec time_interval:573911820) - (invoke count:10000000 tsc_interval:57391174)
[ 326.595307] bench_page_pool_simple: time_bench_page_pool03_slow(): Cannot use page_pool fast-path
[ 328.422661] time_bench: Type:no-softirq-page_pool03 Per elem: 18 cycles(tsc) 181.849 ns (step:0) - (measurement period time:1.818495880 sec time_interval:1818495880) - (invoke count:10000000 tsc_interval:181849581)
[ 328.441681] bench_page_pool_simple: pp_tasklet_handler(): in_serving_softirq fast-path
[ 328.449584] bench_page_pool_simple: time_bench_page_pool01_fast_path(): in_serving_softirq fast-path
[ 328.755031] time_bench: Type:tasklet_page_pool01_fast_path Per elem: 2 cycles(tsc) 29.632 ns (step:0) - (measurement period time:0.296327910 sec time_interval:296327910) - (invoke count:10000000 tsc_interval:29632785)
[ 328.774308] bench_page_pool_simple: time_bench_page_pool02_ptr_ring(): in_serving_softirq fast-path
[ 329.578579] time_bench: Type:tasklet_page_pool02_ptr_ring Per elem: 7 cycles(tsc) 79.523 ns (step:0) - (measurement period time:0.795236560 sec time_interval:795236560) - (invoke count:10000000 tsc_interval:79523650)
[ 329.597769] bench_page_pool_simple: time_bench_page_pool03_slow(): in_serving_softirq fast-path
[ 331.507501] time_bench: Type:tasklet_page_pool03_slow Per elem: 19 cycles(tsc) 190.104 ns (step:0) - (measurement period time:1.901047510 sec time_interval:1901047510) - (invoke count:10000000 tsc_interval:190104743)
After this patchset:
root@(none)$ insmod bench_page_pool_simple.ko
[ 138.634758] bench_page_pool_simple: Loaded
[ 138.715879] time_bench: Type:for_loop Per elem: 0 cycles(tsc) 0.769 ns (step:0) - (measurement period time:0.076972720 sec time_interval:76972720) - (invoke count:100000000 tsc_interval:7697265)
[ 140.079897] time_bench: Type:atomic_inc Per elem: 1 cycles(tsc) 13.467 ns (step:0) - (measurement period time:1.346735370 sec time_interval:1346735370) - (invoke count:100000000 tsc_interval:134673531)
[ 140.247841] time_bench: Type:lock Per elem: 1 cycles(tsc) 15.005 ns (step:0) - (measurement period time:0.150055080 sec time_interval:150055080) - (invoke count:10000000 tsc_interval:15005497)
[ 140.919072] time_bench: Type:rcu Per elem: 0 cycles(tsc) 6.541 ns (step:0) - (measurement period time:0.654125000 sec time_interval:654125000) - (invoke count:100000000 tsc_interval:65412493)
[ 140.936091] bench_page_pool_simple: time_bench_page_pool01_fast_path(): Cannot use page_pool fast-path
[ 141.246985] time_bench: Type:no-softirq-page_pool01 Per elem: 3 cycles(tsc) 30.159 ns (step:0) - (measurement period time:0.301598160 sec time_interval:301598160) - (invoke count:10000000 tsc_interval:30159812)
[ 141.265654] bench_page_pool_simple: time_bench_page_pool02_ptr_ring(): Cannot use page_pool fast-path
[ 141.976265] time_bench: Type:no-softirq-page_pool02 Per elem: 7 cycles(tsc) 70.140 ns (step:0) - (measurement period time:0.701405780 sec time_interval:701405780) - (invoke count:10000000 tsc_interval:70140573)
[ 141.994933] bench_page_pool_simple: time_bench_page_pool03_slow(): Cannot use page_pool fast-path
[ 144.018945] time_bench: Type:no-softirq-page_pool03 Per elem: 20 cycles(tsc) 201.514 ns (step:0) - (measurement period time:2.015141210 sec time_interval:2015141210) - (invoke count:10000000 tsc_interval:201514113)
[ 144.037966] bench_page_pool_simple: pp_tasklet_handler(): in_serving_softirq fast-path
[ 144.045870] bench_page_pool_simple: time_bench_page_pool01_fast_path(): in_serving_softirq fast-path
[ 144.205045] time_bench: Type:tasklet_page_pool01_fast_path Per elem: 1 cycles(tsc) 15.005 ns (step:0) - (measurement period time:0.150056510 sec time_interval:150056510) - (invoke count:10000000 tsc_interval:15005645)
[ 144.224320] bench_page_pool_simple: time_bench_page_pool02_ptr_ring(): in_serving_softirq fast-path
[ 144.916044] time_bench: Type:tasklet_page_pool02_ptr_ring Per elem: 6 cycles(tsc) 68.269 ns (step:0) - (measurement period time:0.682693070 sec time_interval:682693070) - (invoke count:10000000 tsc_interval:68269300)
[ 144.935234] bench_page_pool_simple: time_bench_page_pool03_slow(): in_serving_softirq fast-path
[ 146.997684] time_bench: Type:tasklet_page_pool03_slow Per elem: 20 cycles(tsc) 205.376 ns (step:0) - (measurement period time:2.053766310 sec time_interval:2053766310) - (invoke count:10000000 tsc_interval:205376624)
1. https://lore.kernel.org/lkml/8067f204-1380-4d37-8ffd-007fc6f26738@xxxxxxxxxx/T/
CC: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
CC: Robin Murphy <robin.murphy@xxxxxxx>
CC: Alexander Duyck <alexander.duyck@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: IOMMU <iommu@xxxxxxxxxxxxxxx>
CC: MM <linux-mm@xxxxxxxxx>
Change log:
V7:
1. Fix a used-after-free bug reported by KASAN as mentioned by Jakub.
2. Fix the 'netmem' variable not setting up correctly bug as mentioned
by Simon.
V6:
1. Repost based on latest net-next.
2. Rename page_pool_to_pp() to page_pool_get_pp().
V5:
1. Support unlimit inflight pages.
2. Add some optimization to avoid the overhead of fixing bug.
V4:
1. use scanning to do the unmapping
2. spilt dma sync skipping into separate patch
V3:
1. Target net-next tree instead of net tree.
2. Narrow the rcu lock as the discussion in v2.
3. Check the ummapping cnt against the inflight cnt.
V2:
1. Add a item_full stat.
2. Use container_of() for page_pool_to_pp().
Yunsheng Lin (8):
page_pool: introduce page_pool_get_pp() API
page_pool: fix timing for checking and disabling napi_local
page_pool: fix IOMMU crash when driver has already unbound
page_pool: support unlimited number of inflight pages
page_pool: skip dma sync operation for inflight pages
page_pool: use list instead of ptr_ring for ring cache
page_pool: batch refilling pages to reduce atomic operation
page_pool: use list instead of array for alloc cache
drivers/net/ethernet/freescale/fec_main.c | 8 +-
.../ethernet/google/gve/gve_buffer_mgmt_dqo.c | 2 +-
drivers/net/ethernet/intel/iavf/iavf_txrx.c | 6 +-
drivers/net/ethernet/intel/idpf/idpf_txrx.c | 14 +-
drivers/net/ethernet/intel/libeth/rx.c | 2 +-
.../net/ethernet/mellanox/mlx5/core/en/xdp.c | 3 +-
drivers/net/netdevsim/netdev.c | 6 +-
drivers/net/wireless/mediatek/mt76/mt76.h | 2 +-
include/linux/mm_types.h | 2 +-
include/linux/skbuff.h | 1 +
include/net/libeth/rx.h | 3 +-
include/net/netmem.h | 24 +-
include/net/page_pool/helpers.h | 11 +
include/net/page_pool/types.h | 64 +-
net/core/devmem.c | 4 +-
net/core/netmem_priv.h | 5 +-
net/core/page_pool.c | 664 ++++++++++++++----
net/core/page_pool_priv.h | 12 +-
18 files changed, 675 insertions(+), 158 deletions(-)
