linux-kernel - Re: [PATCH v4 1/6] Documentation: perf: hisi: Documentation for HiSilicon SoC PMU driver

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Message-ID: <20170815095005.GB6090@leverpostej>
Date:   Tue, 15 Aug 2017 10:50:06 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Shaokun Zhang <zhangshaokun@...ilicon.com>
Cc:     will.deacon@....com, jonathan.cameron@...wei.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linuxarm@...wei.com
Subject: Re: [PATCH v4 1/6] Documentation: perf: hisi: Documentation for
 HiSilicon SoC PMU driver

Hi,

On Tue, Jul 25, 2017 at 08:10:37PM +0800, Shaokun Zhang wrote:
> This patch adds documentation for the uncore PMUs on HiSilicon SoC.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Signed-off-by: Shaokun Zhang <zhangshaokun@...ilicon.com>
> Signed-off-by: Anurup M <anurup.m@...wei.com>
> ---
>  Documentation/perf/hisi-pmu.txt | 52 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
>  create mode 100644 Documentation/perf/hisi-pmu.txt
> 
> diff --git a/Documentation/perf/hisi-pmu.txt b/Documentation/perf/hisi-pmu.txt
> new file mode 100644
> index 0000000..f45a03d
> --- /dev/null
> +++ b/Documentation/perf/hisi-pmu.txt
> @@ -0,0 +1,52 @@
> +HiSilicon SoC uncore Performance Monitoring Unit (PMU)
> +======================================================
> +The HiSilicon SoC chip comprehends various independent system device PMUs

Nit: s/comprehends/comprises/ would be easier to read.

> +such as L3 cache (L3C), Hydra Home Agent (HHA) and DDRC. These PMUs are
> +independent and have hardware logic to gather statistics and performance
> +information.
> +
> +HiSilicon SoC encapsulates multiple CPU and IO dies. Each CPU cluster

Nit: The Hisilicon SoC

> +(CCL) is made up of 4 cpu cores sharing one L3 cache; Each CPU die is

Nit: s/Each/each/

> +called Super CPU cluster (SCCL) and is made up of 6 CCLs. Each SCCL has
> +two HHAs (0 - 1) and four DDRCs (0 - 3), respectively.
> +
> +HiSilicon SoC uncore PMU driver
> +---------------------------------------
> +Each device PMU has separate registers for event counting, control and
> +interrupt, and the PMU driver shall register perf PMU drivers like L3C,
> +HHA and DDRC etc. The available events and configuration options shall
> +be described in the sysfs, see /sys/devices/hisi_* 

What exactly its exposed under /sys/devices/hisi_* ?

> or /sys/bus/
> +event_source/devices/hisi_*.

Please don't wrap paths; keep this on one line.

> +The "perf list" command shall list the available events from sysfs.
> +
> +Each L3C, HHA and DDRC in one SCCL are registered as an separate PMU with perf.
> +The PMU name will appear in event listing as hisi_module <index-id>_<sccl-id>.
> +where "index-id" is the index of module and "sccl-id" is the identifier of
> +the SCCL.
> +e.g. hisi_l3c0_1/rd_hit_cpipe is READ_HIT_CPIPE event of L3C index #0 and SCCL
> +ID #1.
> +e.g. hisi_hha0_1/rx_operations is RX_OPERATIONS event of HHA index #0 and SCCL
> +ID #1.

It would make more sense for this to be hierarichal, e.g. hisi_sccl{X}_l3c{Y}.

Other than the above nits, this documentation is very useful. Thanks for
putting this together.

Thanks,
Mark.