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 14:48:55 +0530
From:   Ganapatrao Kulkarni <gklkml16@...il.com>
To:     John Garry <john.garry@...wei.com>
Cc:     Will Deacon <will@...nel.org>,
        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 Fri, Oct 18, 2019 at 2:08 PM John Garry <john.garry@...wei.com> wrote:
>
> 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
>

We don't have such issue at the moment. As i said earlier, the events
exposed are limited.
Total 16 events altogether(DMC, L3C and CCPI2) per socket.

root@...-26>~>> perf list | grep uncore | wc -l
32

> 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
> >
> > .
> >
>
>

Thanks,
Ganapat