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Message-Id: <20180528100259.376465984@linuxfoundation.org>
Date: Mon, 28 May 2018 12:02:15 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Ephraim Park <ephiepark@...com>,
Song Liu <songliubraving@...com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>, jolsa@...hat.com,
kernel-team@...com,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Stephane Eranian <eranian@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Vince Weaver <vincent.weaver@...ne.edu>,
Ingo Molnar <mingo@...nel.org>,
Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.9 206/329] perf/cgroup: Fix child event counting bug
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Song Liu <songliubraving@...com>
[ Upstream commit c917e0f259908e75bd2a65877e25f9d90c22c848 ]
When a perf_event is attached to parent cgroup, it should count events
for all children cgroups:
parent_group <---- perf_event
\
- child_group <---- process(es)
However, in our tests, we found this perf_event cannot report reliable
results. Here is an example case:
# create cgroups
mkdir -p /sys/fs/cgroup/p/c
# start perf for parent group
perf stat -e instructions -G "p"
# on another console, run test process in child cgroup:
stressapptest -s 2 -M 1000 & echo $! > /sys/fs/cgroup/p/c/cgroup.procs
# after the test process is done, stop perf in the first console shows
<not counted> instructions p
The instruction should not be "not counted" as the process runs in the
child cgroup.
We found this is because perf_event->cgrp and cpuctx->cgrp are not
identical, thus perf_event->cgrp are not updated properly.
This patch fixes this by updating perf_cgroup properly for ancestor
cgroup(s).
Reported-by: Ephraim Park <ephiepark@...com>
Signed-off-by: Song Liu <songliubraving@...com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: <jolsa@...hat.com>
Cc: <kernel-team@...com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/20180312165943.1057894-1-songliubraving@fb.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
kernel/events/core.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -634,9 +634,15 @@ static inline void __update_cgrp_time(st
static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
{
- struct perf_cgroup *cgrp_out = cpuctx->cgrp;
- if (cgrp_out)
- __update_cgrp_time(cgrp_out);
+ struct perf_cgroup *cgrp = cpuctx->cgrp;
+ struct cgroup_subsys_state *css;
+
+ if (cgrp) {
+ for (css = &cgrp->css; css; css = css->parent) {
+ cgrp = container_of(css, struct perf_cgroup, css);
+ __update_cgrp_time(cgrp);
+ }
+ }
}
static inline void update_cgrp_time_from_event(struct perf_event *event)
@@ -664,6 +670,7 @@ perf_cgroup_set_timestamp(struct task_st
{
struct perf_cgroup *cgrp;
struct perf_cgroup_info *info;
+ struct cgroup_subsys_state *css;
/*
* ctx->lock held by caller
@@ -674,8 +681,12 @@ perf_cgroup_set_timestamp(struct task_st
return;
cgrp = perf_cgroup_from_task(task, ctx);
- info = this_cpu_ptr(cgrp->info);
- info->timestamp = ctx->timestamp;
+
+ for (css = &cgrp->css; css; css = css->parent) {
+ cgrp = container_of(css, struct perf_cgroup, css);
+ info = this_cpu_ptr(cgrp->info);
+ info->timestamp = ctx->timestamp;
+ }
}
#define PERF_CGROUP_SWOUT 0x1 /* cgroup switch out every event */
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