Tejun Heo 3209e3e812 Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window" ... [ Upstream commit d8ef4b38cb ] 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+ Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-06-07 13:18:46 +02:00
..
Makefile	cgroup: cgroup v2 freezer	2019-04-19 11:26:48 -07:00
cgroup-internal.h	cgroup: make TRACE_CGROUP_PATH irq-safe	2019-04-19 11:26:49 -07:00
cgroup-v1.c	cgroup1: don't call release_agent when it is ""	2020-04-01 11:01:51 +02:00
cgroup.c	cgroup: Iterate tasks that did not finish do_exit()	2020-03-18 07:17:48 +01:00
cpuset.c	sched/topology: Don't try to build empty sched domains	2019-10-29 09:58:45 +01:00
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	2019-12-31 16:45:06 +01:00
legacy_freezer.c	cgroup: rename freezer.c into legacy_freezer.c	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	cgroup: pids: use atomic64_t for pids->limit	2019-12-17 19:56:15 +01:00
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"	2020-06-07 13:18:46 +02:00