linux-kernel - RE: [PATCH] perf metricgroup: Fix system PMU metrics

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Date:   Wed, 20 Jan 2021 05:15:06 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     John Garry <john.garry@...wei.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "acme@...nel.org" <acme@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "jolsa@...hat.com" <jolsa@...hat.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "irogers@...gle.com" <irogers@...gle.com>,
        "kjain@...ux.ibm.com" <kjain@...ux.ibm.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxarm@...neuler.org" <linuxarm@...neuler.org>
Subject: RE: [PATCH] perf metricgroup: Fix system PMU metrics


> -----Original Message-----
> From: John Garry <john.garry@...wei.com>
> Sent: 2021年1月20日 1:33
> To: Joakim Zhang <qiangqing.zhang@....com>; peterz@...radead.org;
> mingo@...hat.com; acme@...nel.org; mark.rutland@....com;
> alexander.shishkin@...ux.intel.com; jolsa@...hat.com;
> namhyung@...nel.org; irogers@...gle.com; kjain@...ux.ibm.com
> Cc: linux-kernel@...r.kernel.org; linuxarm@...neuler.org
> Subject: Re: [PATCH] perf metricgroup: Fix system PMU metrics
> 
> On 19/01/2021 15:47, John Garry wrote:
> > On 19/01/2021 10:56, Joakim Zhang wrote:
> >> It seems have other issue compared to 5.10 kernel after switching to
> >> this framework, below metric can't work.
> >> "MetricExpr": "(( imx8_ddr0@...d\\-cycles@ +
> >> imx8_ddr0@...te\\-cycles@
> >> ) * 4 * 4 / duration_time) / (750 * 1000000 * 4 * 4)"
> >> After change to:
> >> "MetricExpr": "(( imx8mm_ddr.read_cycles + imx8mm_ddr.write_cycles )
> >> *
> >> 4 * 4 / duration_time) / (750 * 1000000 * 4 * 4)",
> >
> > It seems that any metric which includes "duration_time" is broken,
> > even on x86:
> >
> > john@...alhost:~/acme/tools/perf> sudo ./perf stat -v -M
> > L1D_Cache_Fill_BW sleep 1 Using CPUID GenuineIntel-6-3D-4 metric expr
> > 64 * l1d.replacement / 1000000000 / duration_time for
> > L1D_Cache_Fill_BW found event duration_time found event
> > l1d.replacement adding {l1d.replacement}:W,duration_time
> > l1d.replacement -> cpu/umask=0x1,(null)=0x1e8483,event=0x51/
> > Segmentation fault
> >
> >
> > Seems to be from my commit c2337d67199 ("perf metricgroup: Fix metrics
> > using aliases covering multiple PMUs")
> >
> > I'll look to fix it now.
> >
> 
> Please try this:
> 
>  From 2380f1ef0250e6818b3dbc7bff4a868810875e2a Mon Sep 17 00:00:00
> 2001
> From: John Garry <john.garry@...wei.com>
> Date: Tue, 19 Jan 2021 17:29:54 +0000
> Subject: [PATCH] perf metricgroup: Fix metric support for duration_time
> 
> For a metric using duration_time, the strcmp() check when finding identical
> events in metric_events[] is broken, as it does not consider that the
> event pmu_name is NULL - it would be for duration_time.
> 
> As such, add a NULL check here for event pmu_name.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> 
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index ee94d3e8dd65..277adff8017f 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -280,6 +280,8 @@ static struct evsel *find_evsel_group(struct evlist
> *perf_evlist,
>   			 */
>   			if (!has_constraint &&
>   			    ev->leader != metric_events[i]->leader &&
> +			    ev->leader->pmu_name &&
> +			    metric_events[i]->leader->pmu_name &&
>   			    !strcmp(ev->leader->pmu_name,
>   				    metric_events[i]->leader->pmu_name))
>   				break;
> --
> 2.26.2
> 
> 

For this patch: Tested-by: Joakim Zhang <qiangqing.zhang@....com>

Hi John, Jolsa,

Is there any way to avoid breaking exist metric expressions? If not, it will always happened after metricgroup changes.

I recall that Jolsa mentioned it before, but I don’t remember it very clearly.

Thanks a lot for John's bug fix.

Best Regards,
Joakim Zhang