After [1], Only there are 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, we are not only able to unify the page
frag implementation a little, but seems able to have about
0.5+% performance boost testing by using the vhost_net_test
introduced in [1] and page_frag_test.ko introduced in this
patch.
Before this patchset:
Performance counter stats for './vhost_net_test' (10 runs):
603027.29 msec task-clock # 1.756 CPUs utilized ( +- 0.04% )
2097713 context-switches # 3.479 K/sec ( +- 0.00% )
212 cpu-migrations # 0.352 /sec ( +- 4.72% )
40 page-faults # 0.066 /sec ( +- 1.18% )
467215266413 cycles # 0.775 GHz ( +- 0.12% ) (66.02%)
131736729037 stalled-cycles-frontend # 28.20% frontend cycles idle ( +- 2.38% ) (64.34%)
77728393294 stalled-cycles-backend # 16.64% backend cycles idle ( +- 3.98% ) (65.42%)
345874254764 instructions # 0.74 insn per cycle
# 0.38 stalled cycles per insn ( +- 0.75% ) (70.28%)
105166217892 branches # 174.397 M/sec ( +- 0.65% ) (68.56%)
9649321070 branch-misses # 9.18% of all branches ( +- 0.69% ) (65.38%)
343.376 +- 0.147 seconds time elapsed ( +- 0.04% )
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% )
After this patchset:
Performance counter stats for './vhost_net_test' (10 runs):
598081.02 msec task-clock # 1.752 CPUs utilized ( +- 0.11% )
2097738 context-switches # 3.507 K/sec ( +- 0.00% )
220 cpu-migrations # 0.368 /sec ( +- 6.58% )
40 page-faults # 0.067 /sec ( +- 0.92% )
469788205101 cycles # 0.785 GHz ( +- 0.27% ) (64.86%)
137108509582 stalled-cycles-frontend # 29.19% frontend cycles idle ( +- 0.96% ) (63.62%)
75499065401 stalled-cycles-backend # 16.07% backend cycles idle ( +- 1.04% ) (65.86%)
345469451681 instructions # 0.74 insn per cycle
# 0.40 stalled cycles per insn ( +- 0.37% ) (70.16%)
102782224964 branches # 171.853 M/sec ( +- 0.62% ) (69.28%)
9295357532 branch-misses # 9.04% of all branches ( +- 1.08% ) (66.21%)
341.466 +- 0.305 seconds time elapsed ( +- 0.09% )
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% )
CC: Alexander Duyck <alexander.duyck@xxxxxxxxx>
1. https://lore.kernel.org/all/20240228093013.8263-1-linyunsheng@xxxxxxxxxx/
Yunsheng Lin (12):
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: add a test module for page_frag
mm: page_frag: update documentation and maintainer for page_frag
Documentation/mm/page_frags.rst | 115 ++++--
MAINTAINERS | 10 +
.../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 | 339 ++++++++++++++++
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 | 185 +++++++++
mm/page_frag_test.c | 366 ++++++++++++++++++
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 | 4 +-
net/tls/tls_device.c | 139 ++++---
43 files changed, 1404 insertions(+), 572 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
