Commit-ID: 26657848502b78474a5f17f9ce2ae6dc8d8d6262
Gitweb: http://git.kernel.org/tip/26657848502b78474a5f17f9ce2ae6dc8d8d6262
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 22 Mar 2016 22:09:18 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Thu, 31 Mar 2016 10:30:41 +0200
perf/core: Verify we have a single perf_hw_context PMU
There should (and can) only be a single PMU for perf_hw_context
events.
This is because of how we schedule events: once a hardware event fails to
schedule (the PMU is 'full') we stop trying to add more. The trivial
'fix' would break the Round-Robin scheduling we do.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/events/core.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 52bedc5..525d11c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7693,6 +7693,15 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
}
skip_type:
+ if (pmu->task_ctx_nr == perf_hw_context) {
+ static int hw_context_taken = 0;
+
+ if (WARN_ON_ONCE(hw_context_taken))
+ pmu->task_ctx_nr = perf_invalid_context;
+
+ hw_context_taken = 1;
+ }
+
pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
if (pmu->pmu_cpu_context)
goto got_cpu_context;
--
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