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 17:16
> 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 20/01/2021 05:15, Joakim Zhang wrote:
> >
> >> -----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.
> >
> 
> They are not normally broken like that. Normally we test beforehand, but these
> cases were missed here by me. However if you were testing them previously,
> then it would be expected that you had tested them again for the final patchset
> which was merged.


Yes, John, sorry. I have not did the fully test before, this could be avoided.

Best Regards,
Joakim Zhang
> Anyway, we can look to add metric tests for these.
> 
> @Arnaldo, I will send separate formal patch for this today.
> 
> Thanks,
> John