linux-kernel - [RFC 1/2] perf/core: Enable sched

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Date:   Mon,  2 Nov 2020 23:52:20 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephane Eranian <eranian@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Gabriel Marin <gmx@...gle.com>
Subject: [RFC 1/2] perf/core: Enable sched_task callbacks if PMU has it

If an event associated with a PMU which has a sched_task callback,
it should be called regardless of cpu/task context.  For example,
a per-cpu event might enable large PEBS buffers so it needs to flush
the buffer whenever task scheduling happens.

The underlying PMU may or may not require this for the given event,
but it will be handled in the pmu::sched_task() callback anyway.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 kernel/events/core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index b458ed3dc81b..aaa0155c4142 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4696,6 +4696,8 @@ static void unaccount_event(struct perf_event *event)
 		dec = true;
 	if (has_branch_stack(event))
 		dec = true;
+	if (event->pmu->sched_task)
+		dec = true;
 	if (event->attr.ksymbol)
 		atomic_dec(&nr_ksymbol_events);
 	if (event->attr.bpf_event)
@@ -11225,6 +11227,8 @@ static void account_event(struct perf_event *event)
 		inc = true;
 	if (is_cgroup_event(event))
 		inc = true;
+	if (event->pmu->sched_task)
+		inc = true;
 	if (event->attr.ksymbol)
 		atomic_inc(&nr_ksymbol_events);
 	if (event->attr.bpf_event)
-- 
2.29.1.341.ge80a0c044ae-goog