From fd7d55172d1e2e501e6da0a5c1de25f06612dc2e Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Sat, 1 Jun 2019 01:27:22 -0700 Subject: perf/cgroups: Don't rotate events for cgroups unnecessarily Currently perf_rotate_context assumes that if the context's nr_events != nr_active a rotation is necessary for perf event multiplexing. With cgroups, nr_events is the total count of events for all cgroups and nr_active will not include events in a cgroup other than the current task's. This makes rotation appear necessary for cgroups when it is not. Add a perf_event_context flag that is set when rotation is necessary. Clear the flag during sched_out and set it when a flexible sched_in fails due to resources. Signed-off-by: Ian Rogers Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Link: https://lkml.kernel.org/r/20190601082722.44543-1-irogers@google.com Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/perf_event.h') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 3dc01cf98e16..2ddae518dce6 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -749,6 +749,11 @@ struct perf_event_context { int nr_stat; int nr_freq; int rotate_disable; + /* + * Set when nr_events != nr_active, except tolerant to events not + * necessary to be active due to scheduling constraints, such as cgroups. + */ + int rotate_necessary; refcount_t refcount; struct task_struct *task; -- cgit v1.2.3