Tejun Heo a74ebf047e cgroup, rstat: Don't flush subtree root unless necessary ... [ Upstream commit b4ff1b44bc ] cgroup_rstat_cpu_pop_updated() is used to traverse the updated cgroups on flush. While it was only visiting updated ones in the subtree, it was visiting @root unconditionally. We can easily check whether @root is updated or not by looking at its ->updated_next just as with the cgroups in the subtree. * Remove the unnecessary cgroup_parent() test. The system root cgroup is never updated and thus its ->updated_next is always NULL. No need to test whether cgroup_parent() exists in addition to ->updated_next. * Terminate traverse if ->updated_next is NULL. This can only happen for subtree @root and there's no reason to visit it if it's not marked updated. This reduces cpu consumption when reading a lot of rstat backed files. In a micro benchmark reading stat from ~1600 cgroups, the sys time was lowered by >40%. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2019-04-05 22:33:06 +02:00
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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	cgroup/tracing: Move taking of spin lock out of trace event handlers	2018-07-11 10:48:47 -07:00
cgroup.c	fix cgroup_do_mount() handling of failure exits	2019-03-23 20:09:53 +01:00
cpuset.c	docs: Fix some broken references	2018-06-15 18:10:01 -03:00
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: implement cgroup v2 thread support	2017-07-21 11:14:51 -04:00
rdma.c	rdmacg: Convert to use match_string() helper	2018-05-07 09:27:26 -07:00
rstat.c	cgroup, rstat: Don't flush subtree root unless necessary	2019-04-05 22:33:06 +02:00