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| author | Feng Tang <feng.tang@intel.com> | 2021-02-24 12:04:01 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-24 13:38:29 -0800 |
| commit | 802f1d522d5fdaefc2b935141bc8fe03d43a99ab (patch) | |
| tree | bf95df2e8b53d139ed521602b6dba9327594d699 /mm/memcontrol.c | |
| parent | c1a660dea3fa616420606f1e206e6d22f7e05c30 (diff) | |
mm: page_counter: re-layout structure to reduce false sharing
When checking a memory cgroup related performance regression [1], from the
perf c2c profiling data, we found high false sharing for accessing 'usage'
and 'parent'.
On 64 bit system, the 'usage' and 'parent' are close to each other, and
easy to be in one cacheline (for cacheline size == 64+ B). 'usage' is
usally written, while 'parent' is usually read as the cgroup's
hierarchical counting nature.
So move the 'parent' to the end of the structure to make sure they
are in different cache lines.
Following are some performance data with the patch, against v5.11-rc1. [
In the data, A means a platform with 2 sockets 48C/96T, B is a platform of
4 sockests 72C/144T, and if a %stddev will be shown bigger than 2%,
P100/P50 means number of test tasks equals to 100%/50% of nr_cpu]
will-it-scale/malloc1
---------------------
v5.11-rc1 v5.11-rc1+patch
A-P100 15782 ± 2% -0.1% 15765 ± 3% will-it-scale.per_process_ops
A-P50 21511 +8.9% 23432 will-it-scale.per_process_ops
B-P100 9155 +2.2% 9357 will-it-scale.per_process_ops
B-P50 10967 +7.1% 11751 ± 2% will-it-scale.per_process_ops
will-it-scale/pagefault2
------------------------
v5.11-rc1 v5.11-rc1+patch
A-P100 79028 +3.0% 81411 will-it-scale.per_process_ops
A-P50 183960 ± 2% +4.4% 192078 ± 2% will-it-scale.per_process_ops
B-P100 85966 +9.9% 94467 ± 3% will-it-scale.per_process_ops
B-P50 198195 +9.8% 217526 will-it-scale.per_process_ops
fio (4k/1M is block size)
-------------------------
v5.11-rc1 v5.11-rc1+patch
A-P50-r-4k 16881 ± 2% +1.2% 17081 ± 2% fio.read_bw_MBps
A-P50-w-4k 3931 +4.5% 4111 ± 2% fio.write_bw_MBps
A-P50-r-1M 15178 -0.2% 15154 fio.read_bw_MBps
A-P50-w-1M 3924 +0.1% 3929 fio.write_bw_MBps
[1].https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/
Link: https://lkml.kernel.org/r/1611040814-33449-1-git-send-email-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
0 files changed, 0 insertions, 0 deletions