linux-kernel - Re: [PATCH v3 2/2] perf test: Add event group test

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Date:   Wed, 7 Dec 2022 09:56:12 +0530
From:   Ravi Bangoria <ravi.bangoria@....com>
To:     Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        carsten.haitzler@....com, Leo Yan <leo.yan@...aro.org>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        linux-perf-users@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>, sandipan.das@....com,
        ananth.narayan@....com, santosh.shukla@....com,
        Ravi Bangoria <ravi.bangoria@....com>
Subject: Re: [PATCH v3 2/2] perf test: Add event group test

Hi Athira,

>> +static int setup_uncore_event(void)
>> +{
>> +	struct perf_pmu *pmu;
>> +	int i;
>> +
>> +	if (list_empty(&pmus))
>> +		perf_pmu__scan(NULL);
>> +
>> +	perf_pmus__for_each_pmu(pmu) {
>> +		for (i = 0; i < NR_UNCORE_PMUS; i++) {
>> +			if (!strcmp(uncore_pmus[i].name, pmu->name)) {
>> +				pr_debug("Using %s for uncore pmu event\n", pmu->name);
>> +				types[2] = pmu->type;
>> +				configs[2] = uncore_pmus[i].config;
> 
> Hi Ravi,
> 
> Observed failure while running the test on powerpc. It is because the uncore PMU ie hv_24x7 needs
> performance monitoring to be enabled in powerpc. So to handle such cases, can we add an “event_open" check before
> proceeding with the test. Below is the change on top of “tmp.perf/core” .
> 
> 
> From 8b33fb900c26beafc28f75b6f64631f8fdd045c2 Mon Sep 17 00:00:00 2001
> From: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
> Date: Tue, 6 Dec 2022 20:17:25 +0530
> Subject: [PATCH] perf test: Update event group check for support of uncore
>  event
> 
> Event group test checks group creation for combinations of
> hw, sw and uncore PMU events. Some of the uncore pmu event
> requires performance enablement explicitly.

You need to open an event to activate hv_24x7 pmu?

> Example, hv_24x7
> event in powerpc. Hence add a check to see if event_open
> succeeds before proceeding.
> 
> Fixes: 5c88101b797d ("perf test: Add event group test for events in multiple PMUs")
> Signed-off-by: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>
> ---
>  tools/perf/tests/event_groups.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/tests/event_groups.c b/tools/perf/tests/event_groups.c
> index 612c0444aaa8..ad52e1da259a 100644
> --- a/tools/perf/tests/event_groups.c
> +++ b/tools/perf/tests/event_groups.c
> @@ -51,7 +51,7 @@ static int event_open(int type, unsigned long config, int group_fd)
>  static int setup_uncore_event(void)
>  {
>  	struct perf_pmu *pmu;
> -	int i;
> +	int i, fd;
>  
>  	if (list_empty(&pmus))
>  		perf_pmu__scan(NULL);
> @@ -62,6 +62,10 @@ static int setup_uncore_event(void)
>  				pr_debug("Using %s for uncore pmu event\n", pmu->name);
>  				types[2] = pmu->type;
>  				configs[2] = uncore_pmus[i].config;

Sure. Just add a comment here to explain why are we opening a
standalone event here.

> +				fd = event_open(types[2], configs[2], -1);
> +				if (fd < 0)
> +					return -1;
> +				close(fd);
>  				return 0;
>  			}
>  		}

Thanks,
Ravi