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Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for HiSilicon SoC PMU driver

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  Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for  HiSilicon SoC PMU driver Jonathan Cameron <Jonathan.Cameron@huawei.com> - 2017-07-19 11:20 +0200
    Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for  HiSilicon SoC PMU driver Zhangshaokun <zhangshaokun@hisilicon.com> - 2017-07-20 15:00 +0200
      Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for  HiSilicon SoC PMU driver Will Deacon <will.deacon@arm.com> - 2017-07-20 15:10 +0200
        Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for  HiSilicon SoC PMU driver Will Deacon <will.deacon@arm.com> - 2017-07-20 15:20 +0200

#1691154 — Re: [PATCH v3 1/6] Documentation: perf: hisi: Documentation for HiSilicon SoC PMU driver

On Tue, 18 Jul 2017 15:59:54 +0800
Shaokun Zhang <zhangshaokun@hisilicon.com> wrote:

> This patch adds documentation for the uncore PMUs on HiSilicon SoC.
> 
> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
> Signed-off-by: Anurup M <anurup.m@huawei.com>  
Hi Shaokun,

Sorry for the late reply on this (only recently joined Huawei)

This is a fairly generic review of the code rather than going into
the actual userspace ABI choices as this is an area I'm only just
starting to become familiar with.

Thanks,

Jonathan
> ---
>  Documentation/perf/hisi-pmu.txt | 51 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 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..5fa0b1a
> --- /dev/null
> +++ b/Documentation/perf/hisi-pmu.txt
> @@ -0,0 +1,51 @@
> +HiSilicon SoC uncore Performance Monitoring Unit (PMU)
> +======================================================
> +The HiSilicon SoC chip comprehends various independent system device PMUs
> +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 (CC
> +L) is made up of 4 cpu cores sharing one L3 cache; Each CPU die is called  
nitpick, I'd not have a line break mid acronym. 

> +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_*.  
Is there not a subsystem directory that would make more sense to
refer to than the full device list?

> +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.
> +
> +The driver also provides a "cpumask" sysfs attribute, which shows the CPU core
> +ID used to count the uncore PMU event.
> +
> +Example usage of perf:
> +$# perf list
> +hisi_l3c0_3/rd_hit_cpipe/ [kernel PMU event]
> +------------------------------------------
> +hisi_l3c0_3/wr_hit_cpipe/ [kernel PMU event]
> +------------------------------------------
> +hisi_l3c0_1/rd_hit_cpipe/ [kernel PMU event]
> +------------------------------------------
> +hisi_l3c0_1/wr_hit_cpipe/ [kernel PMU event]
> +------------------------------------------
> +
> +$# perf stat -a -e hisi_l3c0_1/rd_hit_cpipe/ sleep 5
> +$# perf stat -a -e hisi_l3c0_1/config=0x02/ sleep 5
> +
> +The current driver does not support sampling. So "perf record" is unsupported.
> +Also attach to a task is unsupported as the events are all uncore.
> +
> +Note: Please contact the maintainer for a complete list of events supported for
> +the PMU devices in the SoC and its information if needed.  


_______________________________________________
linuxarm mailing list

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#1692902

Hi Jonathan,

Thanks for your comments firstly.

On 2017/7/19 17:17, Jonathan Cameron wrote:
> On Tue, 18 Jul 2017 15:59:54 +0800
> Shaokun Zhang <zhangshaokun@hisilicon.com> wrote:
> 
>> This patch adds documentation for the uncore PMUs on HiSilicon SoC.
>>
>> Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
>> Signed-off-by: Anurup M <anurup.m@huawei.com>  
> Hi Shaokun,
> 
> Sorry for the late reply on this (only recently joined Huawei)
> 
> This is a fairly generic review of the code rather than going into
> the actual userspace ABI choices as this is an area I'm only just
> starting to become familiar with.
> 
> Thanks,
> 
> Jonathan
>> ---
>>  Documentation/perf/hisi-pmu.txt | 51 +++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 51 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..5fa0b1a
>> --- /dev/null
>> +++ b/Documentation/perf/hisi-pmu.txt
>> @@ -0,0 +1,51 @@
>> +HiSilicon SoC uncore Performance Monitoring Unit (PMU)
>> +======================================================
>> +The HiSilicon SoC chip comprehends various independent system device PMUs
>> +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 (CC
>> +L) is made up of 4 cpu cores sharing one L3 cache; Each CPU die is called  
> nitpick, I'd not have a line break mid acronym. 
> 

Ok, shall keep CCL in the same line.

>> +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_*.  
> Is there not a subsystem directory that would make more sense to
> refer to than the full device list?
> 

For uncore devices, it is more reasonable to list in /sys/devices/***.

Thanks.
Shaokun

>> +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.
>> +
>> +The driver also provides a "cpumask" sysfs attribute, which shows the CPU core
>> +ID used to count the uncore PMU event.
>> +
>> +Example usage of perf:
>> +$# perf list
>> +hisi_l3c0_3/rd_hit_cpipe/ [kernel PMU event]
>> +------------------------------------------
>> +hisi_l3c0_3/wr_hit_cpipe/ [kernel PMU event]
>> +------------------------------------------
>> +hisi_l3c0_1/rd_hit_cpipe/ [kernel PMU event]
>> +------------------------------------------
>> +hisi_l3c0_1/wr_hit_cpipe/ [kernel PMU event]
>> +------------------------------------------
>> +
>> +$# perf stat -a -e hisi_l3c0_1/rd_hit_cpipe/ sleep 5
>> +$# perf stat -a -e hisi_l3c0_1/config=0x02/ sleep 5
>> +
>> +The current driver does not support sampling. So "perf record" is unsupported.
>> +Also attach to a task is unsupported as the events are all uncore.
>> +
>> +Note: Please contact the maintainer for a complete list of events supported for
>> +the PMU devices in the SoC and its information if needed.  
> 
> 
> _______________________________________________
> linuxarm mailing list
> 
> 
> .
> 

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#1692916

On Thu, Jul 20, 2017 at 08:54:36PM +0800, Zhangshaokun wrote:
> On 2017/7/19 17:17, Jonathan Cameron wrote:
> >> +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_*.  
> > Is there not a subsystem directory that would make more sense to
> > refer to than the full device list?
> > 
> 
> For uncore devices, it is more reasonable to list in /sys/devices/***.

The usual place for these things is /sys/bus/event_source/devices/<pmu name>.

The events are described as files under the events directory (one file per
event, which describes the encoding) and you can describe other things such
as formatting and/or capabilities under other directories too.

Take a look at some other PMU drivers to get an idea of how it works.

Will

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#1692922

On Thu, Jul 20, 2017 at 02:08:47PM +0100, Will Deacon wrote:
> On Thu, Jul 20, 2017 at 08:54:36PM +0800, Zhangshaokun wrote:
> > On 2017/7/19 17:17, Jonathan Cameron wrote:
> > >> +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_*.  
> > > Is there not a subsystem directory that would make more sense to
> > > refer to than the full device list?
> > > 
> > 
> > For uncore devices, it is more reasonable to list in /sys/devices/***.
> 
> The usual place for these things is /sys/bus/event_source/devices/<pmu name>.

... which are symlinks to directories under /sys/devices/! I didn't realise
that, so I suspect you're ok. Still worth getting the format of things
correct though, so perf can read/parse them with minimal effort.

Will

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