linux-kernel - Re: [PATCH v6 03/10] perf/x86/rapl: Remove the cpu_to_rapl

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Message-ID: <Zx9RHtFAURrORTrd@BLRRASHENOY1.amd.com>
Date: Mon, 28 Oct 2024 14:23:50 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
Cc: peterz@...radead.org, mingo@...hat.com, rui.zhang@...el.com,
	acme@...nel.org, namhyung@...nel.org, mark.rutland@....com,
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	irogers@...gle.com, adrian.hunter@...el.com,
	kan.liang@...ux.intel.com, tglx@...utronix.de, bp@...en8.de,
	dave.hansen@...ux.intel.com, ananth.narayan@....com,
	kprateek.nayak@....com, ravi.bangoria@....com, x86@...nel.org,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 03/10] perf/x86/rapl: Remove the cpu_to_rapl_pmu()
 function

Hello Dhananjay,

On Fri, Oct 25, 2024 at 11:13:41AM +0000, Dhananjay Ugwekar wrote:
> Prepare for the addition of RAPL core energy counter support.
> Post which, one CPU might be mapped to more than one rapl_pmu
> (package/die one and a core one). So, remove the cpu_to_rapl_pmu()
> function.
> 
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
> ---
>  arch/x86/events/rapl.c | 19 ++++++-------------
>  1 file changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
> index f70c49ca0ef3..d20c5b1dd0ad 100644
> --- a/arch/x86/events/rapl.c
> +++ b/arch/x86/events/rapl.c
> @@ -162,17 +162,6 @@ static inline unsigned int get_rapl_pmu_idx(int cpu)
>  					 topology_logical_die_id(cpu);
>  }
>  
> -static inline struct rapl_pmu *cpu_to_rapl_pmu(unsigned int cpu)
> -{
> -	unsigned int rapl_pmu_idx = get_rapl_pmu_idx(cpu);
> -
> -	/*
> -	 * The unsigned check also catches the '-1' return value for non
> -	 * existent mappings in the topology map.
> -	 */


See the comment here why rapl_pmu_idx should be an "unsigned int".


> -	return rapl_pmu_idx < rapl_pmus->nr_rapl_pmu ? rapl_pmus->pmus[rapl_pmu_idx] : NULL;
> -}
> -
>  static inline u64 rapl_read_counter(struct perf_event *event)
>  {
>  	u64 raw;
> @@ -348,7 +337,7 @@ static void rapl_pmu_event_del(struct perf_event *event, int flags)
>  static int rapl_pmu_event_init(struct perf_event *event)
>  {
>  	u64 cfg = event->attr.config & RAPL_EVENT_MASK;
> -	int bit, ret = 0;
> +	int bit, rapl_pmu_idx, ret = 0;

Considering that, shouldn't rapl_pmu_idx be an "unsigned int" no?

--
Thanks and Regards
gautham.


>  	struct rapl_pmu *pmu;
>  
>  	/* only look at RAPL events */
> @@ -376,8 +365,12 @@ static int rapl_pmu_event_init(struct perf_event *event)
>  	if (event->attr.sample_period) /* no sampling */
>  		return -EINVAL;
>  
> +	rapl_pmu_idx = get_rapl_pmu_idx(event->cpu);
> +	if (rapl_pmu_idx >= rapl_pmus->nr_rapl_pmu)
> +		return -EINVAL;
> +
>  	/* must be done before validate_group */
> -	pmu = cpu_to_rapl_pmu(event->cpu);
> +	pmu = rapl_pmus->pmus[rapl_pmu_idx];
>  	if (!pmu)
>  		return -EINVAL;
>  	event->pmu_private = pmu;
> -- 
> 2.34.1
>