Commit 53b25335 authored May 16, 2014 by Vince Weaver Committed by Ingo Molnar Jun 05, 2014

perf: Disable sampled events if no PMU interrupt



Add common code to generate -ENOTSUPP at event creation time if an
architecture attempts to create a sampled event and
PERF_PMU_NO_INTERRUPT is set.

This adds a new pmu->capabilities flag.  Initially we only support
PERF_PMU_NO_INTERRUPT (to indicate a PMU has no support for generating
hardware interrupts) but there are other capabilities that can be
added later.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Acked-by: Will Deacon <will.deacon@arm.com>
[peterz: rename to PERF_PMU_CAP_* and moved the pmu::capabilities word into a hole]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1405161708060.11099@vincent-weaver-1.umelst.maine.edu


Signed-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent ebf905fc

include/linux/perf_event.h

+10 −0

Original line number	Diff line number	Diff line
		@@ -166,6 +166,11 @@ struct perf_event;
		*/
		#define PERF_EVENT_TXN 0x1

		/**
		* pmu::capabilities flags
		*/
		#define PERF_PMU_CAP_NO_INTERRUPT 0x01

		/**
		* struct pmu - generic performance monitoring unit
		*/
		@@ -178,6 +183,11 @@ struct pmu {
		const char *name;
		int type;

		/*
		* various common per-pmu feature flags
		*/
		int capabilities;

		int * __percpu pmu_disable_count;
		struct perf_cpu_context * __percpu pmu_cpu_context;
		int task_ctx_nr;

kernel/events/core.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -7120,6 +7120,13 @@ SYSCALL_DEFINE5(perf_event_open,
		}
		}

		if (is_sampling_event(event)) {
		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
		err = -ENOTSUPP;
		goto err_alloc;
		}
		}

		account_event(event);

		/*

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