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From: James Clark <james.clark@arm.com>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org
Cc: James Clark <james.clark@arm.com>, Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>, Al Grant <al.grant@arm.com>,
	Leo Yan <leo.yan@linaro.org>, John Garry <john.garry@huawei.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: [PATCH] drivers/perf: Enable PID_IN_CONTEXTIDR with SPE
Date: Mon, 30 Nov 2020 18:24:54 +0200	[thread overview]
Message-ID: <20201130162454.28255-1-james.clark@arm.com> (raw)

Enable PID_IN_CONTEXTIDR by default when Arm SPE is enabled.
This flag is required to get PID data in the SPE trace. Without
it the perf tool will report 0 for PID which isn't very useful,
especially when doing system wide profiling or profiling
applications that fork.

There is a small performance overhead when enabling
PID_IN_CONTEXTIDR, but SPE itself is optional and not enabled by
default so the impact is minimised.

Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Al Grant <al.grant@arm.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: John Garry <john.garry@huawei.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
 drivers/perf/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
index 130327ff0b0e..47ede46c3d57 100644
--- a/drivers/perf/Kconfig
+++ b/drivers/perf/Kconfig
@@ -125,6 +125,7 @@ config XGENE_PMU
 config ARM_SPE_PMU
 	tristate "Enable support for the ARMv8.2 Statistical Profiling Extension"
 	depends on ARM64
+	select PID_IN_CONTEXTIDR
 	help
 	  Enable perf support for the ARMv8.2 Statistical Profiling
 	  Extension, which provides periodic sampling of operations in
-- 
2.28.0


             reply	other threads:[~2020-11-30 16:26 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-30 16:24 James Clark [this message]
2020-11-30 16:46 ` Will Deacon
2020-12-01  4:10   ` Leo Yan
2020-12-01 23:09     ` Will Deacon
2020-12-03  6:39       ` Leo Yan
2020-12-03  6:41         ` Leo Yan
2020-12-04  0:07         ` Mathieu Poirier
2020-12-14  8:51       ` James Clark

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