Commit 085b3062 authored Sep 23, 2016 by Will Deacon

perf/core: Add PERF_AUX_FLAG_COLLISION to report colliding samples



The ARM SPE architecture permits an implementation to ignore a sample
if the sample is due to be taken whilst another sample is already being
produced. In this case, it is desirable to report the collision to
userspace, as they may want to lower the sample period.

This patch adds a PERF_AUX_FLAG_COLLISION flag, so that such events can
be relayed to userspace.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent bc1d2020

include/uapi/linux/perf_event.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -941,6 +941,7 @@ enum perf_callchain_context {
		#define PERF_AUX_FLAG_TRUNCATED 0x01 /* record was truncated to fit */
		#define PERF_AUX_FLAG_OVERWRITE 0x02 /* snapshot from overwrite mode */
		#define PERF_AUX_FLAG_PARTIAL 0x04 /* record contains gaps */
		#define PERF_AUX_FLAG_COLLISION 0x08 /* sample collided with another */

		#define PERF_FLAG_FD_NO_GROUP (1UL << 0)
		#define PERF_FLAG_FD_OUTPUT (1UL << 1)