linux-kernel - Re: [PATCH] perf pmu: Fix parser error for uncore event alias

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Date:   Mon, 18 Mar 2019 09:53:22 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     kan.liang@...ux.intel.com
Cc:     acme@...nel.org, mingo@...hat.com, linux-kernel@...r.kernel.org,
        ak@...ux.intel.com, Thomas Richter <tmricht@...ux.ibm.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH] perf pmu: Fix parser error for uncore event alias

On Fri, Mar 15, 2019 at 11:00:14AM -0700, kan.liang@...ux.intel.com wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> Perf fails to parse uncore event alias, for example:
> 
>   #perf stat -e unc_m_clockticks -a --no-merge sleep 1
>   event syntax error: 'unc_m_clockticks'
>                        \___ parser error
> 
> Current code assumes that the event alias is from one specific PMU.
> To find the PMU, perf strcmp the pmu name of event alias with the
> real pmu name on the system.
> However, the uncore event alias may be from multiple PMUs with common
> prefix. The pmu name of uncore event alias is the common prefix.
> For example, UNC_M_CLOCKTICKS is clock event for iMC, which include
> 6 PMUs with the same prefix "uncore_imc" on a skylake server.
> The real pmu names on the system for iMC are uncore_imc_0 ...
> uncore_imc_5.
> The strncmp is used to only check the common prefix for uncore
> event alias.
> 
> With the patch,
>   #perf stat -e unc_m_clockticks -a --no-merge sleep 1
>   Performance counter stats for 'system wide':
> 
>        723,594,722      unc_m_clockticks [uncore_imc_5]
>        724,001,954      unc_m_clockticks [uncore_imc_3]
>        724,042,655      unc_m_clockticks [uncore_imc_1]
>        724,161,001      unc_m_clockticks [uncore_imc_4]
>        724,293,713      unc_m_clockticks [uncore_imc_2]
>        724,340,901      unc_m_clockticks [uncore_imc_0]
> 
>        1.002090060 seconds time elapsed
> 
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> Cc: Thomas Richter <tmricht@...ux.ibm.com>
> Cc: stable@...r.kernel.org
> Fixes: ea1fa48c055f ("perf stat: Handle different PMU names with common prefix")

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka

> ---
>  tools/perf/util/pmu.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 51d437f..395308f 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -732,10 +732,20 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
>  
>  		if (!is_arm_pmu_core(name)) {
>  			pname = pe->pmu ? pe->pmu : "cpu";
> +
> +			/*
> +			 * uncore alias may be from different PMU
> +			 * with common prefix
> +			 */
> +			if (pmu_is_uncore(name) &&
> +			    !strncmp(pname, name, strlen(pname)))
> +				goto new_alias;
> +
>  			if (strcmp(pname, name))
>  				continue;
>  		}
>  
> +new_alias:
>  		/* need type casts to override 'const' */
>  		__perf_pmu__new_alias(head, NULL, (char *)pe->name,
>  				(char *)pe->desc, (char *)pe->event,
> -- 
> 2.7.4
>