Commit d0d1dd62 authored by Namhyung Kim's avatar Namhyung Kim Committed by Peter Zijlstra
Browse files

perf core: Add PERF_COUNT_SW_CGROUP_SWITCHES event 



This patch adds a new software event to count context switches
involving cgroup switches.  So it's counted only if cgroups of
previous and next tasks are different.  Note that it only checks the
cgroups in the perf_event subsystem.  For cgroup v2, it shouldn't
matter anyway.

One can argue that we can do this by using existing sched_switch event
with eBPF.  But some systems might not have eBPF for some reason so
I'd like to add this as a simple way.

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210210083327.22726-2-namhyung@kernel.org
parent 7c8056bb

include/linux/perf_event.h

+7 −0
Original line number Diff line number Diff line
@@ -1218,6 +1218,13 @@ static inline void perf_event_task_sched_out(struct task_struct *prev, 
	if (__perf_sw_enabled(PERF_COUNT_SW_CONTEXT_SWITCHES))

		__perf_sw_event_sched(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 0);



#ifdef CONFIG_CGROUP_PERF

	if (__perf_sw_enabled(PERF_COUNT_SW_CGROUP_SWITCHES) &&

	    perf_cgroup_from_task(prev, NULL) !=

	    perf_cgroup_from_task(next, NULL))

		__perf_sw_event_sched(PERF_COUNT_SW_CGROUP_SWITCHES, 1, 0);

#endif



	if (static_branch_unlikely(&perf_sched_events))

		__perf_event_task_sched_out(prev, next);

}

include/uapi/linux/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ enum perf_sw_ids { 
	PERF_COUNT_SW_EMULATION_FAULTS		= 8,

	PERF_COUNT_SW_DUMMY			= 9,

	PERF_COUNT_SW_BPF_OUTPUT		= 10,

	PERF_COUNT_SW_CGROUP_SWITCHES		= 11,



	PERF_COUNT_SW_MAX,			/* non-ABI */

};