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perf: fix perf_event_context->time 

Time readers rely on perf_event_context->[time|timestamp|timeoffset] to get
accurate time_enabled and time_running for an event. The difference between
ctx->timestamp and ctx->time is the among of time when the context is not
enabled. __update_context_time(ctx, false) is used to increase timestamp,
but not time. Therefore, it should only be called in ctx_sched_in() when
EVENT_TIME was not enabled.

Fixes: 09f5e7dc7a ("perf: Fix perf_event_read_local() time")
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/r/20230313171608.298734-1-song@kernel.org
This commit is contained in:
Song Liu 2023-03-13 10:16:08 -07:00 committed by Peter Zijlstra
parent eb81a2ed4f
commit baf1b12a67
1 changed files with 1 additions and 1 deletions
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2
kernel/events/core.c
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@ -3872,7 +3872,7 @@ ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type)
if (likely(!ctx->nr_events))
return;
if (is_active ^ EVENT_TIME) {
if (!(is_active & EVENT_TIME)) {
/* start ctx time */
__update_context_time(ctx, false);
perf_cgroup_set_timestamp(cpuctx);