linux-kernel - Re: [PATCH v3 11/27] perf pmu: Support 'cycles' and 'branches' inside hybrid PMU

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Message-ID: <YHBbJEKjE3DuPvZZ@krava>
Date:   Fri, 9 Apr 2021 15:48:20 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jin Yao <yao.jin@...ux.intel.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v3 11/27] perf pmu: Support 'cycles' and 'branches'
 inside hybrid PMU

On Mon, Mar 29, 2021 at 03:00:30PM +0800, Jin Yao wrote:
> On hybrid platform, user may want to enable the hardware event
> only on one PMU. So following syntax is supported:
> 
> cpu_core/<hardware event>/
> cpu_atom/<hardware event>/
> 
>   # perf stat -e cpu_core/cpu-cycles/ -a -- sleep 1
> 
>    Performance counter stats for 'system wide':
> 
>            6,049,336      cpu_core/cpu-cycles/
> 
>          1.003577042 seconds time elapsed
> 
> It enables the event 'cpu-cycles' only on cpu_core pmu.
> 
> But for 'cycles' and 'branches', the syntax doesn't work.

because the alias is not there.. but there's:
  cpu/cpu-cycles/
  cpu/branch-instructions/

doing the same thing..  what's wrong with that?

I have a feeling we discussed this in the previous
version.. did I give up? ;-)

SNIP

> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index beff29981101..72e5ae5e868e 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -916,6 +916,35 @@ static int pmu_max_precise(const char *name)
>  	return max_precise;
>  }
>  
> +static void perf_pmu__add_hybrid_aliases(struct list_head *head)
> +{
> +	static struct pmu_event pme_hybrid_fixup[] = {
> +		{
> +			.name = "cycles",
> +			.event = "event=0x3c",
> +		},
> +		{
> +			.name = "branches",
> +			.event = "event=0xc4",
> +		},
> +		{
> +			.name = 0,
> +			.event = 0,
> +		},

if you really need to access these 2 events with special name,
why not add it through the json.. let's not have yet another
place that defines aliases ... also this should be model specific
no?

jirka