linux-kernel - Re: [PATCH V2 08/25] perf/x86: Hybrid PMU support for hardware cache event

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Date:   Thu, 11 Mar 2021 12:07:03 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     kan.liang@...ux.intel.com
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org, acme@...nel.org,
        tglx@...utronix.de, bp@...en8.de, namhyung@...nel.org,
        jolsa@...hat.com, ak@...ux.intel.com, yao.jin@...ux.intel.com,
        alexander.shishkin@...ux.intel.com, adrian.hunter@...el.com
Subject: Re: [PATCH V2 08/25] perf/x86: Hybrid PMU support for hardware cache
 event

On Wed, Mar 10, 2021 at 08:37:44AM -0800, kan.liang@...ux.intel.com wrote:
> From: Kan Liang <kan.liang@...ux.intel.com>
> 
> The hardware cache events are different among hybrid PMUs. Each hybrid
> PMU should have its own hw cache event table.
> 
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
> ---
>  arch/x86/events/core.c       | 11 +++++++++--
>  arch/x86/events/perf_event.h |  9 +++++++++
>  2 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index 039a851..1db4a67 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -352,6 +352,7 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>  {
>  	struct perf_event_attr *attr = &event->attr;
>  	unsigned int cache_type, cache_op, cache_result;
> +	struct x86_hybrid_pmu *pmu = is_hybrid() ? hybrid_pmu(event->pmu) : NULL;
>  	u64 config, val;
>  
>  	config = attr->config;
> @@ -371,7 +372,10 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>  		return -EINVAL;
>  	cache_result = array_index_nospec(cache_result, PERF_COUNT_HW_CACHE_RESULT_MAX);
>  
> -	val = hw_cache_event_ids[cache_type][cache_op][cache_result];
> +	if (pmu)
> +		val = pmu->hw_cache_event_ids[cache_type][cache_op][cache_result];
> +	else
> +		val = hw_cache_event_ids[cache_type][cache_op][cache_result];
>  
>  	if (val == 0)
>  		return -ENOENT;
> @@ -380,7 +384,10 @@ set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
>  		return -EINVAL;
>  
>  	hwc->config |= val;
> -	attr->config1 = hw_cache_extra_regs[cache_type][cache_op][cache_result];
> +	if (pmu)
> +		attr->config1 = pmu->hw_cache_extra_regs[cache_type][cache_op][cache_result];
> +	else
> +		attr->config1 = hw_cache_extra_regs[cache_type][cache_op][cache_result];

Why not:

	attr->config1 = hybrid(event->pmu, hw_cache_extra_regs)[cache_type][cache_op][cache_result];

?