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

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Date:   Tue, 19 Jan 2021 17:33:13 +0000
From:   John Garry <john.garry@...wei.com>
To:     Joakim Zhang <qiangqing.zhang@....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

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