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authorSong Liu <songliubraving@fb.com>2018-05-03 22:47:16 +0300
committerIngo Molnar <mingo@kernel.org>2018-05-25 09:11:10 +0300
commita1150c202207cc8501bebc45b63c264f91959260 (patch)
tree17b8820b35d29a2e82875b8339ca036fe6452db2 /include/linux/perf_event.h
parentbd9c67ad9693bacef086d65c1c6744645d4777e7 (diff)
downloadlinux-a1150c202207cc8501bebc45b63c264f91959260.tar.xz
perf/core: Fix group scheduling with mixed hw and sw events
When hw and sw events are mixed in the same group, they are all attached to the hw perf_event_context. This sometimes requires moving group of perf_event to a different context. We found a bug in how the kernel handles this, for example if we do: perf stat -e '{faults,ref-cycles,faults}' -I 1000 1.005591180 1,297 faults 1.005591180 457,476,576 ref-cycles 1.005591180 <not supported> faults First, sw event "faults" is attached to the sw context, and becomes the group leader. Then, hw event "ref-cycles" is attached, so both events are moved to the hw context. Last, another sw "faults" tries to attach, but it fails because of mismatch between the new target ctx (from sw pmu) and the group_leader's ctx (hw context, same as ref-cycles). The broken condition is: group_leader is sw event; group_leader is on hw context; add a sw event to the group. Fix this scenario by checking group_leader's context (instead of just event type). If group_leader is on hw context, use the ->pmu of this context to look up context for the new event. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: <kernel-team@fb.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Fixes: b04243ef7006 ("perf: Complete software pmu grouping") Link: http://lkml.kernel.org/r/20180503194716.162815-1-songliubraving@fb.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/perf_event.h')
-rw-r--r--include/linux/perf_event.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index e71e99eb9a4e..def866f7269b 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1016,6 +1016,14 @@ static inline int is_software_event(struct perf_event *event)
return event->event_caps & PERF_EV_CAP_SOFTWARE;
}
+/*
+ * Return 1 for event in sw context, 0 for event in hw context
+ */
+static inline int in_software_context(struct perf_event *event)
+{
+ return event->ctx->pmu->task_ctx_nr == perf_sw_context;
+}
+
extern struct static_key perf_swevent_enabled[PERF_COUNT_SW_MAX];
extern void ___perf_sw_event(u32, u64, struct pt_regs *, u64);