RE: [PATCH] perf metricgroup: Fix system PMU metrics

[Joakim Zhang]

> -----Original Message-----
> From: John Garry <john.garry@xxxxxxxxxx>
> Sent: 2021年1月20日 1:33
> To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; peterz@xxxxxxxxxxxxx;
> mingo@xxxxxxxxxx; acme@xxxxxxxxxx; mark.rutland@xxxxxxx;
> alexander.shishkin@xxxxxxxxxxxxxxx; jolsa@xxxxxxxxxx;
> namhyung@xxxxxxxxxx; irogers@xxxxxxxxxx; kjain@xxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linuxarm@xxxxxxxxxxxxx
> 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@read\\-cycles@ +
> >> imx8_ddr0@write\\-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@localhost:~/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@xxxxxxxxxx>
> 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@xxxxxxxxxx>
> 
> 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@xxxxxxx>

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