Tejun Heo 7cbf0e5cea Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window" ... [ Upstream commit d8ef4b38cb69d907f9b0e889c44d05fc0f890977 ] 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 13:17:53 +02:00
..
cgroup-internal.h	cgroup/tracing: Move taking of spin lock out of trace event handlers	2018-07-11 10:48:47 -07:00
cgroup-v1.c	cgroup1: don't call release_agent when it is ""	2020-04-02 15:28:14 +02:00
cgroup.c	cgroup: Iterate tasks that did not finish do_exit()	2020-03-18 07:14:19 +01:00
cpuset.c	cpuset: restore sanity to cpuset_cpus_allowed_fallback()	2019-07-10 09:53:39 +02:00
debug.c	debug cgroup: use task_css_set instead of rcu_dereference	2017-11-27 11:37:33 -08:00
freezer.c	cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS	2017-07-21 11:14:51 -04:00
Makefile	cgroup: Rename kernel/cgroup/stat.c to kernel/cgroup/rstat.c	2018-04-26 14:29:04 -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 20:34:56 +01:00
rdma.c	rdmacg: Convert to use match_string() helper	2018-05-07 09:27:26 -07:00
rstat.c	Revert "cgroup: Add memory barriers to plug cgroup_rstat_updated() race window"	2020-06-07 13:17:53 +02:00