Commit cc6795ae authored Jan 10, 2019 by Andrew Murray Committed by Ingo Molnar Jan 21, 2019

perf/core: Add PERF_PMU_CAP_NO_EXCLUDE for exclusion incapable PMUs



Many PMU drivers do not have the capability to exclude counting events
that occur in specific contexts such as idle, kernel, guest, etc. These
drivers indicate this by returning an error in their event_init upon
testing the events attribute flags. This approach is error prone and
often inconsistent.

Let's instead allow PMU drivers to advertise their inability to exclude
based on context via a new capability: PERF_PMU_CAP_NO_EXCLUDE. This
allows the perf core to reject requests for exclusion events where
there is no support in the PMU.

Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: robin.murphy@arm.com
Cc: suzuki.poulose@arm.com
Link: https://lkml.kernel.org/r/1547128414-50693-4-git-send-email-andrew.murray@arm.com


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

parent 486efe9f

include/linux/perf_event.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -244,6 +244,7 @@ struct perf_event;
		#define PERF_PMU_CAP_EXCLUSIVE 0x10
		#define PERF_PMU_CAP_ITRACE 0x20
		#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x40
		#define PERF_PMU_CAP_NO_EXCLUDE 0x80

		/**
		* struct pmu - generic performance monitoring unit

kernel/events/core.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -9772,6 +9772,15 @@ static int perf_try_init_event(struct pmu pmu, struct perf_event event)
		if (ctx)
		perf_event_ctx_unlock(event->group_leader, ctx);

		if (!ret) {
		if (pmu->capabilities & PERF_PMU_CAP_NO_EXCLUDE &&
		event_has_any_exclude_flag(event)) {
		if (event->destroy)
		event->destroy(event);
		ret = -EINVAL;
		}
		}

		if (ret)
		module_put(pmu->module);

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