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Subject[PATCH v2 6/6] perf/core: Don't need event_filter_match when merge_sched_in()
Date
There are two obselete comments in perf_cgroup_switch(), since
we don't use event_filter_match() when event_sched_out(). And
found we needn't to use event_filter_match() when sched_in too.

Because now we use the perf_event groups RB-tree to get the
exact matched perf_events, don't need to go through the
event_filter_match() to check if matched.

We can remove it in merge_sched_in() actually, but this patch
changes it to a WARN_ON_ONCE for debug purpose, and found
no warning in our stress test.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
kernel/events/core.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 4c8657b08301..744078fe2819 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -860,15 +860,11 @@ static void perf_cgroup_switch(struct task_struct *task)
perf_pmu_disable(cpuctx->ctx.pmu);

cpu_ctx_sched_out(cpuctx, EVENT_ALL);
- /*
- * must not be done before ctxswout due
- * to event_filter_match() in event_sched_out()
- */
cpuctx->cgrp = cgrp;
/*
* set cgrp before ctxsw in to allow
- * event_filter_match() to not have to pass
- * task around
+ * visit_groups_merge() to find matched
+ * cgroup events
*/
cpu_ctx_sched_in(cpuctx, EVENT_ALL);

@@ -3729,7 +3725,7 @@ static int merge_sched_in(struct perf_event *event, void *data)
if (event->state <= PERF_EVENT_STATE_OFF)
return 0;

- if (!event_filter_match(event))
+ if (WARN_ON_ONCE(!event_filter_match(event)))
return 0;

if (group_can_go_on(event, cpuctx, *can_add_hw)) {
--
2.20.1
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