Commit 49925c1c authored by Ji Sheng Teoh's avatar Ji Sheng Teoh Committed by Will Deacon
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docs: perf: Add description for StarFive's StarLink PMU 



StarFive StarLink PMU support monitoring L3 memory system PMU events.
Add documentation to describe StarFive StarLink PMU support and it's
usage.

Signed-off-by: default avatarJi Sheng Teoh <jisheng.teoh@starfivetech.com>
Link: https://lore.kernel.org/r/20240229072720.3987876-4-jisheng.teoh@starfivetech.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 66461b43

Documentation/admin-guide/perf/index.rst

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@@ -13,6 +13,7 @@ Performance monitor support 
   imx-ddr

   qcom_l2_pmu

   qcom_l3_pmu

   starfive_starlink_pmu

   arm-ccn

   arm-cmn

   xgene-pmu

Documentation/admin-guide/perf/starfive_starlink_pmu.rst

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================================================

StarFive StarLink Performance Monitor Unit (PMU)

================================================



StarFive StarLink Performance Monitor Unit (PMU) exists within the

StarLink Coherent Network on Chip (CNoC) that connects multiple CPU

clusters with an L3 memory system.



The uncore PMU supports overflow interrupt, up to 16 programmable 64bit

event counters, and an independent 64bit cycle counter.

The PMU can only be accessed via Memory Mapped I/O and are common to the

cores connected to the same PMU.



Driver exposes supported PMU events in sysfs "events" directory under::



  /sys/bus/event_source/devices/starfive_starlink_pmu/events/



Driver exposes cpu used to handle PMU events in sysfs "cpumask" directory

under::



  /sys/bus/event_source/devices/starfive_starlink_pmu/cpumask/



Driver describes the format of config (event ID) in sysfs "format" directory

under::



  /sys/bus/event_source/devices/starfive_starlink_pmu/format/



Example of perf usage::



	$ perf list



	starfive_starlink_pmu/cycles/                      [Kernel PMU event]

	starfive_starlink_pmu/read_hit/                    [Kernel PMU event]

	starfive_starlink_pmu/read_miss/                   [Kernel PMU event]

	starfive_starlink_pmu/read_request/                [Kernel PMU event]

	starfive_starlink_pmu/release_request/             [Kernel PMU event]

	starfive_starlink_pmu/write_hit/                   [Kernel PMU event]

	starfive_starlink_pmu/write_miss/                  [Kernel PMU event]

	starfive_starlink_pmu/write_request/               [Kernel PMU event]

	starfive_starlink_pmu/writeback/                   [Kernel PMU event]





	$ perf stat -a -e /starfive_starlink_pmu/cycles/ sleep 1



Sampling is not supported. As a result, "perf record" is not supported.

Attaching to a task is not supported, only system-wide counting is supported.