Tejun Heo d8ef4b38cb Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window" ... This reverts commit 9a9e97b2f1 ("cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"). The commit was added in anticipation of memcg rstat conversion which needed synchronous accounting for the event counters (e.g. oom kill count). However, the conversion didn't get merged due to percpu memory overhead concern which couldn't be addressed at the time. Unfortunately, the patch's addition of smp_mb() to cgroup_rstat_updated() meant that every scheduling event now had to go through an additional full barrier and Mel Gorman noticed it as 1% regression in netperf UDP_STREAM test. There's no need to have this barrier in tree now and even if we need synchronous accounting in the future, the right thing to do is separating that out to a separate function so that hot paths which don't care about synchronous behavior don't have to pay the overhead of the full barrier. Let's revert. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Mel Gorman <mgorman@techsingularity.net> Link: http://lkml.kernel.org/r/20200409154413.GK3818@techsingularity.net Cc: v4.18+		2020-04-09 14:55:46 -04:00
..
cgroup-internal.h	fs_parse: fold fs_parameter_desc/fs_parameter_spec	2020-02-07 14:48:37 -05:00
cgroup-v1.c	cgroup: Restructure release_agent_path handling	2020-03-12 16:44:35 -04:00
cgroup.c	Merge branch 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup	2020-04-03 11:30:20 -07:00
cpuset.c	docs: cgroup-v1: Document the cpuset_v2_mode mount option	2020-04-03 11:42:56 -04:00
debug.c	kernel: cgroup: fix misuse of %x	2019-05-06 08:47:48 -07:00
freezer.c	cgroup: freezer: don't change task and cgroups status unnecessarily	2019-11-07 07:38:41 -08:00
legacy_freezer.c	cgroup: rename freezer.c into legacy_freezer.c	2019-04-19 11:26:48 -07:00
Makefile	cgroup: cgroup v2 freezer	2019-04-19 11:26:48 -07:00
namespace.c	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
pids.c	clone3: allow spawning processes into cgroups	2020-02-12 17:57:51 -05:00
rdma.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 451	2019-06-19 17:09:08 +02:00
rstat.c	Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"	2020-04-09 14:55:46 -04:00