linux-kernel - Re: [PATCH v6 2/2] drivers/perf: Add CCPI2 PMU support in ThunderX2 UNCORE driver.

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Date:   Fri, 18 Oct 2019 09:38:06 +0100
From:   John Garry <john.garry@...wei.com>
To:     Ganapatrao Kulkarni <gklkml16@...il.com>,
        Will Deacon <will@...nel.org>
CC:     Ganapatrao Prabhakerrao Kulkarni <gkulkarni@...vell.com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "corbet@....net" <corbet@....net>,
        Jan Glauber <jglauber@...vell.com>,
        Jayachandran Chandrasekharan Nair <jnair@...vell.com>,
        Robert Richter <rrichter@...vell.com>,
        Zhangshaokun <zhangshaokun@...ilicon.com>
Subject: Re: [PATCH v6 2/2] drivers/perf: Add CCPI2 PMU support in ThunderX2
 UNCORE driver.

On 18/10/2019 05:21, Ganapatrao Kulkarni wrote:
> Hi Will,
>
> On Thu, Oct 17, 2019 at 9:17 PM Will Deacon <will@...nel.org> wrote:
>>
>> On Thu, Oct 17, 2019 at 12:38:51PM +0530, Ganapatrao Kulkarni wrote:
>>> On Wed, Oct 16, 2019 at 7:01 PM John Garry <john.garry@...wei.com> wrote:
>>>>> +TX2_EVENT_ATTR(req_pktsent, CCPI2_EVENT_REQ_PKT_SENT);
>>>>> +TX2_EVENT_ATTR(snoop_pktsent, CCPI2_EVENT_SNOOP_PKT_SENT);
>>>>> +TX2_EVENT_ATTR(data_pktsent, CCPI2_EVENT_DATA_PKT_SENT);
>>>>> +TX2_EVENT_ATTR(gic_pktsent, CCPI2_EVENT_GIC_PKT_SENT);
>>>>> +
>>>>> +static struct attribute *ccpi2_pmu_events_attrs[] = {
>>>>> +     &tx2_pmu_event_attr_req_pktsent.attr.attr,
>>>>> +     &tx2_pmu_event_attr_snoop_pktsent.attr.attr,
>>>>> +     &tx2_pmu_event_attr_data_pktsent.attr.attr,
>>>>> +     &tx2_pmu_event_attr_gic_pktsent.attr.attr,
>>>>> +     NULL,
>>>>> +};
>>>>
>>>> Hi Ganapatrao,
>>>>
>>>> Have you considered adding these as uncore pmu-events in the perf tool?
>>>>
>>> At the moment no, since the number of events exposed/listed are very few.
>>
>> Then sounds like a perfect time to nip it in the bud before the list grows
>> ;)
>
> I had internal discussion with architecture team, they have confirmed
> that, these are the only published events and no plan to add new.
> However, If any such request comes from HW team in future, i will add
> them to JSON files.

Don't you find perf list is swamped with all the uncore events?

For Huawei platform, I find this:
./perf list pmu | grep "Kernel PMU event" | grep hisi | wc -l
648

That's because we have so many instances of the same PMUs, not because 
there are many events per PMU.

TBH, I would like to delete all the events from the hisi uncore kernel 
drivers, now that they're supported in the perf tool, but I think that 
would constitute an ABI breakage.

Maybe there is a way to hide them, but I couldn't find it.

John

>
> I have incorporate all your previous comments, Can you please Ack and
> queue it to 5.5?
>
>>
>> If you can manage with these things in userspace, then I agree with John
>> that it would be preferential to do it that way. It also offers more
>> flexibility if we get the metricgroup stuff working properly (I think it's
>> buggered for big/little atm).
>>
>> Will
>
> Thanks,
> Ganapat
>
> .
>