linux-kernel - Re: [RESEND PATCH v4 4/4] powerpc/papr_scm: Document papr

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Date:   Thu, 9 Sep 2021 13:33:22 +0530
From:   kajoljain <kjain@...ux.ibm.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Linux NVDIMM <nvdimm@...ts.linux.dev>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Weiny, Ira" <ira.weiny@...el.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        maddy@...ux.ibm.com, Santosh Sivaraj <santosh@...six.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Vaibhav Jain <vaibhav@...ux.ibm.com>,
        atrajeev@...ux.vnet.ibm.com, Thomas Gleixner <tglx@...utronix.de>,
        rnsastry@...ux.ibm.com
Subject: Re: [RESEND PATCH v4 4/4] powerpc/papr_scm: Document papr_scm sysfs
 event format entries



On 9/8/21 6:33 AM, Dan Williams wrote:
> On Thu, Sep 2, 2021 at 10:11 PM Kajol Jain <kjain@...ux.ibm.com> wrote:
>>
>> Details is added for the event, cpumask and format attributes
>> in the ABI documentation.
>>
>> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>> Reviewed-by: Madhavan Srinivasan <maddy@...ux.ibm.com>
>> Tested-by: Nageswara R Sastry <rnsastry@...ux.ibm.com>
>> Signed-off-by: Kajol Jain <kjain@...ux.ibm.com>
>> ---
>>  Documentation/ABI/testing/sysfs-bus-papr-pmem | 31 +++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-papr-pmem b/Documentation/ABI/testing/sysfs-bus-papr-pmem
>> index 95254cec92bf..4d86252448f8 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-papr-pmem
>> +++ b/Documentation/ABI/testing/sysfs-bus-papr-pmem
>> @@ -61,3 +61,34 @@ Description:
>>                 * "CchRHCnt" : Cache Read Hit Count
>>                 * "CchWHCnt" : Cache Write Hit Count
>>                 * "FastWCnt" : Fast Write Count
>> +
>> +What:          /sys/devices/nmemX/format
>> +Date:          June 2021
>> +Contact:       linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, nvdimm@...ts.linux.dev,
>> +Description:   (RO) Attribute group to describe the magic bits
>> +                that go into perf_event_attr.config for a particular pmu.
>> +                (See ABI/testing/sysfs-bus-event_source-devices-format).
>> +
>> +                Each attribute under this group defines a bit range of the
>> +                perf_event_attr.config. Supported attribute is listed
>> +                below::
>> +
>> +                   event  = "config:0-4"  - event ID
>> +
>> +               For example::
>> +                   noopstat = "event=0x1"
>> +
>> +What:          /sys/devices/nmemX/events
> 
> That's not a valid sysfs path. Did you mean /sys/bus/nd/devices/nmemX?

Hi Dan,
  Thanks, I will correct it and update it to `/sys/bus/event_source/devices/`
where perf creates sysfs files for given pmu.

> 
>> +Date:          June 2021
>> +Contact:       linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, nvdimm@...ts.linux.dev,
>> +Description:    (RO) Attribute group to describe performance monitoring
>> +                events specific to papr-scm. Each attribute in this group describes
>> +                a single performance monitoring event supported by this nvdimm pmu.
>> +                The name of the file is the name of the event.
>> +                (See ABI/testing/sysfs-bus-event_source-devices-events).
> 
> Given these events are in the generic namespace the ABI documentation
> should be generic as well. So I think move these entries to
> Documentation/ABI/testing/sysfs-bus-nvdimm directly.
> 
> You can still mention papr-scm, but I would expect something like:
> 
> What:           /sys/bus/nd/devices/nmemX/events
> Date:           September 2021
> KernelVersion:  5.16
> Contact:        Kajol Jain <kjain@...ux.ibm.com>
> Description:
>                 (RO) Attribute group to describe performance monitoring events
>                 for the nvdimm memory device. Each attribute in this group
>                 describes a single performance monitoring event supported by
>                 this nvdimm pmu.  The name of the file is the name of the event.
>                 (See ABI/testing/sysfs-bus-event_source-devices-events). A
>                 listing of the events supported by a given nvdimm provider type
>                 can be found in Documentation/driver-api/nvdimm/$provider, for
>                 example: Documentation/driver-api/nvdimm/papr-scm.
> 
> 

I will update it accordingly.

> 
>> +
>> +What:          /sys/devices/nmemX/cpumask
>> +Date:          June 2021
>> +Contact:       linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>, nvdimm@...ts.linux.dev,
>> +Description:   (RO) This sysfs file exposes the cpumask which is designated to make
>> +                HCALLs to retrieve nvdimm pmu event counter data.
> 
> Seems this one would be provider generic, so no need to refer to PPC
> specific concepts like HCALLs.
> 

Sure will update it.

Thanks,
Kajol Jain