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Message-ID: <20120906132346.GA32717@quad> Date: Thu, 6 Sep 2012 15:23:46 +0200 From: Stephane Eranian <eranian@...gle.com> To: linux-kernel@...r.kernel.org Cc: peterz@...radead.org, mingo@...e.hu, fweisbec@...il.com Subject: [PATCH] perf: remove sw events from multiplexing rotation list Software events (sw,tracepoints,...) do not need to be multiplexed. However, when using a SW event, the SW PMU (TYPE_SOFTWARE, TYPE_TRACEPOINT) was added to the per-cpu rotation_list. That list is used by perf_rotate_context() to iterate over all the PMUs to rotate event lists and multiplex. This is not needed for SW events. Doing this adds some unnecessary overhead, so drop it by rejecting SW PMUs in perf_pmu_rotate_start(). Signed-off-by: Stephane Eranian <eranian@...gle.com> --- diff --git a/kernel/events/core.c b/kernel/events/core.c index 7b9df35..40f42b8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -651,6 +651,10 @@ static void perf_pmu_rotate_start(struct pmu *pmu) struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); struct list_head *head = &__get_cpu_var(rotation_list); + /* no need to mutliplex software events */ + if (pmu->task_ctx_nr == perf_sw_context) + return; + WARN_ON(!irqs_disabled()); if (list_empty(&cpuctx->rotation_list)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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