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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@infradead.org>
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>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-03-22 22:09:18 +01:00 committed by Ingo Molnar
parent 07dc900e17
commit 2665784850
1 changed files with 9 additions and 0 deletions
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9
kernel/events/core.c
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@ -7693,6 +7693,15 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
} }
skip_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); pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
if (pmu->pmu_cpu_context) if (pmu->pmu_cpu_context)
goto got_cpu_context; goto got_cpu_context;