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,
will@kernel.org, leo.yan@linaro.org
Cc: James Clark <james.clark@arm.com>,
Mark Rutland <mark.rutland@arm.com>, Al Grant <al.grant@arm.com>,
John Garry <john.garry@huawei.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>
Subject: [PATCH v2] drivers/perf: Enable PID_IN_CONTEXTIDR with SPE
Date: Mon, 14 Dec 2020 10:45:02 +0200 [thread overview]
Message-ID: <20201214084502.19954-1-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>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Clark <james.clark@arm.com>
---
arch/arm64/Kconfig.debug | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index 265c4461031f..b030bb21a0bb 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug
@@ -2,6 +2,7 @@
config PID_IN_CONTEXTIDR
bool "Write the current PID to the CONTEXTIDR register"
+ default y if ARM_SPE_PMU
help
Enabling this option causes the kernel to write the current PID to
the CONTEXTIDR register, at the expense of some additional
--
2.28.0
next reply other threads:[~2020-12-14 8:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 8:45 James Clark [this message]
2021-01-06 10:24 ` [PATCH v2] drivers/perf: Enable PID_IN_CONTEXTIDR with SPE Mark Rutland
2021-01-07 18:00 ` Al Grant
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