From: Song Liu song@kernel.org
[ Upstream commit baf1b12a67f5b24f395baca03e442ce27cab0c18 ]
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: 09f5e7dc7ad7 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 002eb9b9faa09..fad170b475921 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -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);