From 26657848502b78474a5f17f9ce2ae6dc8d8d6262 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 22 Mar 2016 22:09:18 +0100 Subject: [PATCH] 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) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- kernel/events/core.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 52bedc5a5aaa..525d11c59287 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; -- 2.30.2