linux-kernel - [PATCH v5 3/3] docs: perf: Add description for StarFive's StarLink PMU

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Message-ID: <20231207142940.1794032-4-jisheng.teoh@starfivetech.com>
Date:   Thu, 7 Dec 2023 22:29:40 +0800
From:   Ji Sheng Teoh <jisheng.teoh@...rfivetech.com>
To:     Jonathan Corbet <corbet@....net>, Will Deacon <will@...nel.org>,
        "Mark Rutland" <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Ilkka Koskinen" <ilkka@...amperecomputing.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Dave Jiang <dave.jiang@...el.com>
CC:     Ji Sheng Teoh <jisheng.teoh@...rfivetech.com>,
        Ley Foon Tan <leyfoon.tan@...rfivetech.com>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>
Subject: [PATCH v5 3/3] 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: Ji Sheng Teoh <jisheng.teoh@...rfivetech.com>
---
 Documentation/admin-guide/perf/index.rst      |  1 +
 .../perf/starfive_starlink_pmu.rst            | 46 +++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 Documentation/admin-guide/perf/starfive_starlink_pmu.rst

diff --git a/Documentation/admin-guide/perf/index.rst b/Documentation/admin-guide/perf/index.rst
index a2e6f2c81146..c5de7579a71b 100644
--- a/Documentation/admin-guide/perf/index.rst
+++ b/Documentation/admin-guide/perf/index.rst
@@ -13,6 +13,7 @@ Performance monitor support
    imx-ddr
    qcom_l2_pmu
    qcom_l3_pmu
+   starfive_starlink_pmu
    arm-ccn
    arm-cmn
    xgene-pmu
diff --git a/Documentation/admin-guide/perf/starfive_starlink_pmu.rst b/Documentation/admin-guide/perf/starfive_starlink_pmu.rst
new file mode 100644
index 000000000000..2932ddb4eb76
--- /dev/null
+++ b/Documentation/admin-guide/perf/starfive_starlink_pmu.rst
@@ -0,0 +1,46 @@
+================================================
+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.
-- 
2.25.1