summaryrefslogtreecommitdiffstats
path: root/kernel/events
diff options
context:
space:
mode:
authorSong Liu <songliubraving@fb.com>2018-05-03 12:47:16 -0700
committerIngo Molnar <mingo@kernel.org>2018-05-25 08:11:10 +0200
commita1150c202207cc8501bebc45b63c264f91959260 (patch)
tree17b8820b35d29a2e82875b8339ca036fe6452db2 /kernel/events
parentbd9c67ad9693bacef086d65c1c6744645d4777e7 (diff)
downloadlinux-a1150c202207cc8501bebc45b63c264f91959260.tar.bz2
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 'kernel/events')
-rw-r--r--kernel/events/core.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 67612ce359ad..ce6aa5ff3c96 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10521,19 +10521,20 @@ SYSCALL_DEFINE5(perf_event_open,
if (pmu->task_ctx_nr == perf_sw_context)
event->event_caps |= PERF_EV_CAP_SOFTWARE;
- if (group_leader &&
- (is_software_event(event) != is_software_event(group_leader))) {
- if (is_software_event(event)) {
+ if (group_leader) {
+ if (is_software_event(event) &&
+ !in_software_context(group_leader)) {
/*
- * If event and group_leader are not both a software
- * event, and event is, then group leader is not.
+ * If the event is a sw event, but the group_leader
+ * is on hw context.
*
- * Allow the addition of software events to !software
- * groups, this is safe because software events never
- * fail to schedule.
+ * Allow the addition of software events to hw
+ * groups, this is safe because software events
+ * never fail to schedule.
*/
- pmu = group_leader->pmu;
- } else if (is_software_event(group_leader) &&
+ pmu = group_leader->ctx->pmu;
+ } else if (!is_software_event(event) &&
+ is_software_event(group_leader) &&
(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
/*
* In case the group is a pure software group, and we