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authorSong Liu <song@kernel.org>2023-03-13 10:16:08 -0700
committerPeter Zijlstra <peterz@infradead.org>2023-03-15 21:49:46 +0100
commitbaf1b12a67f5b24f395baca03e442ce27cab0c18 (patch)
treef9712ff14ca14f51daf9ec21bc3b534f55040fcc /kernel
parenteb81a2ed4f52be831c9fb879752d89645a312c13 (diff)
downloadlwn-baf1b12a67f5b24f395baca03e442ce27cab0c18.tar.gz
lwn-baf1b12a67f5b24f395baca03e442ce27cab0c18.zip
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: 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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 296617edbda1..52b4aa0b3bd1 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);