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author | Song Liu <songliubraving@fb.com> | 2018-03-12 09:59:43 -0700 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-03-20 08:58:47 +0100 |
commit | c917e0f259908e75bd2a65877e25f9d90c22c848 (patch) | |
tree | 00130de15db1164c02b285cde32818ad3c51127a /kernel/events | |
parent | 320b0651f32b830add6497fcdcfdcb6ae8c7b8a0 (diff) | |
download | linux-c917e0f259908e75bd2a65877e25f9d90c22c848.tar.gz |
perf/cgroup: Fix child event counting bug
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@fb.com> Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <jolsa@redhat.com> Cc: <kernel-team@fb.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/20180312165943.1057894-1-songliubraving@fb.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events')
-rw-r--r-- | kernel/events/core.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index 4b838470fac4..709a55b9ad97 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -724,9 +724,15 @@ static inline void __update_cgrp_time(struct perf_cgroup *cgrp) 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) @@ -754,6 +760,7 @@ perf_cgroup_set_timestamp(struct task_struct *task, { struct perf_cgroup *cgrp; struct perf_cgroup_info *info; + struct cgroup_subsys_state *css; /* * ctx->lock held by caller @@ -764,8 +771,12 @@ perf_cgroup_set_timestamp(struct task_struct *task, 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; + } } static DEFINE_PER_CPU(struct list_head, cgrp_cpuctx_list); |