[PATCH net-next v2 00/15] First try to replace page_frag with page_frag_cache
From: Yunsheng Lin
Date: Mon Apr 15 2024 - 09:29:57 EST
After [1], there are still two implementations for page frag:
1. mm/page_alloc.c: net stack seems to be using it in the
rx part with 'struct page_frag_cache' and the main API
being page_frag_alloc_align().
2. net/core/sock.c: net stack seems to be using it in the
tx part with 'struct page_frag' and the main API being
skb_page_frag_refill().
This patchset tries to unfiy the page frag implementation
by replacing page_frag with page_frag_cache for sk_page_frag()
first. net_high_order_alloc_disable_key for the implementation
in net/core/sock.c doesn't seems matter that much now have
have pcp support for high-order pages in commit 44042b449872
("mm/page_alloc: allow high-order pages to be stored on the
per-cpu lists").
As the related change is mostly related to networking, so
targeting the net-next. And will try to replace the rest
of page_frag in the follow patchset.
After this patchset:
1. Unify the page frag implementation by taking the best out of
two the existing implementations: we are able to save some space
for the 'page_frag_cache' API user, and avoid 'get_page()' for
the old 'page_frag' API user.
2. Future bugfix and performance can be done in one place, hence
improving maintainability of page_frag's implementation.
Performance validation:
1. Using micro-benchmark ko added in patch 1, we have about 3.2%
performance boot for the 'page_frag_cache' after this patchset.
2. Use the below netcat test case, we have about 1.9% performance
boot for repalcing 'page_frag' with 'page_frag_cache' after this
patchset.
server: nc -l -k 1234 > /dev/null
client: perf stat -r 30 -- head -c 51200000000 /dev/zero | nc -N 127.0.0.1 1234
In order to avoid performance noise as much as possible, the testing
is done in system without any other laod and have enough iterations to
prove the data is stable enogh, complete log for testing is below:
*After* this patchset:
insmod ./page_frag_test.ko nr_test=99999999
Performance counter stats for 'insmod ./page_frag_test.ko nr_test=99999999' (30 runs):
40.09 msec task-clock # 0.001 CPUs utilized ( +- 4.60% )
5 context-switches # 124.722 /sec ( +- 3.45% )
1 cpu-migrations # 24.944 /sec ( +- 12.62% )
197 page-faults # 4.914 K/sec ( +- 0.11% )
10221721 cycles # 0.255 GHz ( +- 9.05% ) (27.73%)
2459009 stalled-cycles-frontend # 24.06% frontend cycles idle ( +- 10.80% ) (29.05%)
5148423 stalled-cycles-backend # 50.37% backend cycles idle ( +- 7.30% ) (82.47%)
5889929 instructions # 0.58 insn per cycle
# 0.87 stalled cycles per insn ( +- 11.85% ) (87.75%)
1276667 branches # 31.846 M/sec ( +- 11.48% ) (89.80%)
50631 branch-misses # 3.97% of all branches ( +- 8.72% ) (83.20%)
29.341 +- 0.300 seconds time elapsed ( +- 1.02% )
perf stat -r 30 -- head -c 51200000000 /dev/zero | nc -N 127.0.0.1 1234
Performance counter stats for 'head -c 51200000000 /dev/zero' (30 runs):
107793.53 msec task-clock # 0.881 CPUs utilized ( +- 0.36% )
380421 context-switches # 3.529 K/sec ( +- 0.32% )
374 cpu-migrations # 3.470 /sec ( +- 1.31% )
74 page-faults # 0.686 /sec ( +- 0.28% )
92758718093 cycles # 0.861 GHz ( +- 0.48% ) (69.47%)
7035559641 stalled-cycles-frontend # 7.58% frontend cycles idle ( +- 1.19% ) (69.65%)
33668082825 stalled-cycles-backend # 36.30% backend cycles idle ( +- 0.84% ) (70.18%)
52424770535 instructions # 0.57 insn per cycle
# 0.64 stalled cycles per insn ( +- 0.26% ) (61.93%)
13240874953 branches # 122.836 M/sec ( +- 0.40% ) (60.36%)
208178019 branch-misses # 1.57% of all branches ( +- 0.65% ) (68.42%)
122.294 +- 0.402 seconds time elapsed ( +- 0.33% )
*Before* this patchset:
insmod ./page_frag_test.ko nr_test=99999999
Performance counter stats for 'insmod ./page_frag_test.ko nr_test=99999999' (30 runs):
39.12 msec task-clock # 0.001 CPUs utilized ( +- 4.51% )
5 context-switches # 127.805 /sec ( +- 3.76% )
1 cpu-migrations # 25.561 /sec ( +- 15.52% )
197 page-faults # 5.035 K/sec ( +- 0.10% )
10689913 cycles # 0.273 GHz ( +- 9.46% ) (72.72%)
2821237 stalled-cycles-frontend # 26.39% frontend cycles idle ( +- 12.04% ) (76.23%)
5035549 stalled-cycles-backend # 47.11% backend cycles idle ( +- 9.69% ) (49.40%)
5439395 instructions # 0.51 insn per cycle
# 0.93 stalled cycles per insn ( +- 11.58% ) (51.45%)
1274419 branches # 32.575 M/sec ( +- 12.69% ) (77.88%)
49562 branch-misses # 3.89% of all branches ( +- 9.91% ) (72.32%)
30.309 +- 0.305 seconds time elapsed ( +- 1.01% )
perf stat -r 30 -- head -c 51200000000 /dev/zero | nc -N 127.0.0.1 1234
Performance counter stats for 'head -c 51200000000 /dev/zero' (30 runs):
110198.93 msec task-clock # 0.884 CPUs utilized ( +- 0.83% )
387680 context-switches # 3.518 K/sec ( +- 0.85% )
366 cpu-migrations # 3.321 /sec ( +- 11.38% )
74 page-faults # 0.672 /sec ( +- 0.27% )
92978008685 cycles # 0.844 GHz ( +- 0.49% ) (64.93%)
7339938950 stalled-cycles-frontend # 7.89% frontend cycles idle ( +- 1.48% ) (67.15%)
34783792329 stalled-cycles-backend # 37.41% backend cycles idle ( +- 1.52% ) (68.96%)
51704527141 instructions # 0.56 insn per cycle
# 0.67 stalled cycles per insn ( +- 0.37% ) (68.28%)
12865503633 branches # 116.748 M/sec ( +- 0.88% ) (66.11%)
212414695 branch-misses # 1.65% of all branches ( +- 0.45% ) (64.57%)
124.664 +- 0.990 seconds time elapsed ( +- 0.79% )
Note, ipv4-udp, ipv6-tcp and ipv6-udp is also tested with the below script:
nc -u -l -k 1234 > /dev/null
perf stat -r 4 -- head -c 51200000000 /dev/zero | nc -N -u 127.0.0.1 1234
nc -l6 -k 1234 > /dev/null
perf stat -r 4 -- head -c 51200000000 /dev/zero | nc -N ::1 1234
nc -l6 -k -u 1234 > /dev/null
perf stat -r 4 -- head -c 51200000000 /dev/zero | nc -u -N ::1 1234
Change log:
V2:
1. reorder test module to patch 1.
2. split doc and maintainer updating to two patches.
3. refactor the page_frag before moving.
4. fix a type and 'static' warning in test module.
5. add a patch for xtensa arch to enable using get_order() in
BUILD_BUG_ON().
6. Add test case and performance data for the socket code.
Yunsheng Lin (15):
mm: page_frag: add a test module for page_frag
xtensa: remove the get_order() implementation
mm: page_frag: use free_unref_page() to free page fragment
mm: move the page fragment allocator from page_alloc into its own file
mm: page_frag: use initial zero offset for page_frag_alloc_align()
mm: page_frag: change page_frag_alloc_* API to accept align param
mm: page_frag: add '_va' suffix to page_frag API
mm: page_frag: add two inline helper for page_frag API
mm: page_frag: reuse MSB of 'size' field for pfmemalloc
mm: page_frag: reuse existing bit field of 'va' for pagecnt_bias
net: introduce the skb_copy_to_va_nocache() helper
mm: page_frag: introduce prepare/commit API for page_frag
net: replace page_frag with page_frag_cache
mm: page_frag: update documentation for page_frag
mm: page_frag: add a entry in MAINTAINERS for page_frag
Documentation/mm/page_frags.rst | 148 ++++++-
MAINTAINERS | 11 +
arch/xtensa/include/asm/page.h | 18 -
.../chelsio/inline_crypto/chtls/chtls.h | 3 -
.../chelsio/inline_crypto/chtls/chtls_io.c | 101 ++---
.../chelsio/inline_crypto/chtls/chtls_main.c | 3 -
drivers/net/ethernet/google/gve/gve_rx.c | 4 +-
drivers/net/ethernet/intel/ice/ice_txrx.c | 2 +-
drivers/net/ethernet/intel/ice/ice_txrx.h | 2 +-
drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 2 +-
.../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 4 +-
.../marvell/octeontx2/nic/otx2_common.c | 2 +-
drivers/net/ethernet/mediatek/mtk_wed_wo.c | 4 +-
drivers/net/tun.c | 34 +-
drivers/nvme/host/tcp.c | 8 +-
drivers/nvme/target/tcp.c | 22 +-
drivers/vhost/net.c | 6 +-
include/linux/gfp.h | 22 --
include/linux/mm_types.h | 18 -
include/linux/page_frag_cache.h | 344 +++++++++++++++++
include/linux/sched.h | 4 +-
include/linux/skbuff.h | 15 +-
include/net/sock.h | 29 +-
kernel/bpf/cpumap.c | 2 +-
kernel/exit.c | 3 +-
kernel/fork.c | 2 +-
mm/Kconfig.debug | 8 +
mm/Makefile | 2 +
mm/page_alloc.c | 136 -------
mm/page_frag_cache.c | 154 ++++++++
mm/page_frag_test.c | 365 ++++++++++++++++++
net/core/skbuff.c | 57 +--
net/core/skmsg.c | 22 +-
net/core/sock.c | 46 ++-
net/core/xdp.c | 2 +-
net/ipv4/ip_output.c | 35 +-
net/ipv4/tcp.c | 35 +-
net/ipv4/tcp_output.c | 28 +-
net/ipv6/ip6_output.c | 35 +-
net/kcm/kcmsock.c | 30 +-
net/mptcp/protocol.c | 74 ++--
net/rxrpc/txbuf.c | 16 +-
net/sunrpc/svcsock.c | 6 +-
net/tls/tls_device.c | 139 ++++---
44 files changed, 1450 insertions(+), 553 deletions(-)
create mode 100644 include/linux/page_frag_cache.h
create mode 100644 mm/page_frag_cache.c
create mode 100644 mm/page_frag_test.c
--
2.33.0