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.
Kernel Image changing:
Linux Kernel total | text data bss
------------------------------------------------------
after 44893035 | 27084547 17042328 766160
before 44896899 | 27088459 17042280 766160
delta -3864 | -3912 +48 +0
Performance validation:
1. Using micro-benchmark ko added in patch 1 to test aligned and
non-aligned API performance impact for the existing users, there
is no notiable performance degradation. Instead we have some minor
performance boot for both aligned and non-aligned API after this
patchset as below.
2. Use the below netcat test case, we also have some minor
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:
Performance counter stats for 'insmod ./page_frag_test.ko' (200 runs):
17.959047 task-clock (msec) # 0.001 CPUs utilized ( +- 0.16% )
7 context-switches # 0.371 K/sec ( +- 0.52% )
1 cpu-migrations # 0.037 K/sec ( +- 5.25% )
84 page-faults # 0.005 M/sec ( +- 0.10% )
46630340 cycles # 2.596 GHz ( +- 0.16% )
60991298 instructions # 1.31 insn per cycle ( +- 0.03% )
14778609 branches # 822.906 M/sec ( +- 0.03% )
21461 branch-misses # 0.15% of all branches ( +- 0.35% )
25.071309168 seconds time elapsed ( +- 0.42% )
Performance counter stats for 'insmod ./page_frag_test.ko test_align=1' (200 runs):
17.518324 task-clock (msec) # 0.001 CPUs utilized ( +- 0.22% )
7 context-switches # 0.397 K/sec ( +- 0.22% )
0 cpu-migrations # 0.014 K/sec ( +- 12.78% )
84 page-faults # 0.005 M/sec ( +- 0.10% )
45494458 cycles # 2.597 GHz ( +- 0.22% )
61059177 instructions # 1.34 insn per cycle ( +- 0.02% )
14792330 branches # 844.392 M/sec ( +- 0.02% )
21132 branch-misses # 0.14% of all branches ( +- 0.17% )
26.156288028 seconds time elapsed ( +- 0.41% )
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:
Performance counter stats for 'insmod ./page_frag_test_frag_page_v3_org.ko' (200 runs):
17.878013 task-clock (msec) # 0.001 CPUs utilized ( +- 0.02% )
7 context-switches # 0.384 K/sec ( +- 0.37% )
0 cpu-migrations # 0.002 K/sec ( +- 34.73% )
83 page-faults # 0.005 M/sec ( +- 0.11% )
46428731 cycles # 2.597 GHz ( +- 0.02% )
61080812 instructions # 1.32 insn per cycle ( +- 0.01% )
14802110 branches # 827.951 M/sec ( +- 0.01% )
33011 branch-misses # 0.22% of all branches ( +- 0.10% )
26.923903379 seconds time elapsed ( +- 0.32% )
Performance counter stats for 'insmod ./page_frag_test_frag_page_v3_org.ko test_align=1' (200 runs):
17.579978 task-clock (msec) # 0.001 CPUs utilized ( +- 0.05% )
7 context-switches # 0.393 K/sec ( +- 0.31% )
0 cpu-migrations # 0.014 K/sec ( +- 12.96% )
83 page-faults # 0.005 M/sec ( +- 0.10% )
45649145 cycles # 2.597 GHz ( +- 0.05% )
60999424 instructions # 1.34 insn per cycle ( +- 0.03% )
14778647 branches # 840.652 M/sec ( +- 0.03% )
33148 branch-misses # 0.22% of all branches ( +- 0.11% )
27.454413570 seconds time elapsed ( +- 0.48% )
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
CC: Alexander Duyck <alexander.duyck@gmail.com>
Change log:
v3:
1. Use new layout for 'struct page_frag_cache' as the discussion
with Alexander and other sugeestions from Alexander.
2. Add probe API to address Mat' comment about mptcp use case.
3. Some doc updating according to Bagas' suggestion.
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 (13):
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: add '_va' suffix to page_frag API
mm: page_frag: avoid caller accessing 'page_frag_cache' directly
mm: page_frag: reuse existing space for 'size' and 'pfmemalloc'
net: introduce the skb_copy_to_va_nocache() helper
mm: page_frag: introduce prepare/probe/commit API
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 | 156 ++++++-
MAINTAINERS | 11 +
arch/xtensa/include/asm/page.h | 18 -
.../chelsio/inline_crypto/chtls/chtls.h | 3 -
.../chelsio/inline_crypto/chtls/chtls_io.c | 100 ++---
.../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 | 28 +-
drivers/nvme/host/tcp.c | 8 +-
drivers/nvme/target/tcp.c | 22 +-
drivers/vhost/net.c | 8 +-
include/linux/gfp.h | 22 -
include/linux/mm_types.h | 18 -
include/linux/page_frag_cache.h | 278 +++++++++++++
include/linux/sched.h | 4 +-
include/linux/skbuff.h | 3 +-
include/net/sock.h | 29 +-
kernel/bpf/cpumap.c | 2 +-
kernel/exit.c | 3 +-
kernel/fork.c | 3 +-
mm/Kconfig.debug | 8 +
mm/Makefile | 2 +
mm/page_alloc.c | 136 -------
mm/page_frag_cache.c | 337 ++++++++++++++++
mm/page_frag_test.c | 379 ++++++++++++++++++
net/core/skbuff.c | 56 +--
net/core/skmsg.c | 22 +-
net/core/sock.c | 46 ++-
net/core/xdp.c | 2 +-
net/ipv4/ip_output.c | 33 +-
net/ipv4/tcp.c | 35 +-
net/ipv4/tcp_output.c | 28 +-
net/ipv6/ip6_output.c | 33 +-
net/kcm/kcmsock.c | 30 +-
net/mptcp/protocol.c | 70 ++--
net/rxrpc/conn_object.c | 4 +-
net/rxrpc/local_object.c | 4 +-
net/rxrpc/txbuf.c | 15 +-
net/sched/em_meta.c | 2 +-
net/sunrpc/svcsock.c | 12 +-
net/tls/tls_device.c | 139 ++++---
47 files changed, 1576 insertions(+), 556 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