linux-kernel - Re: [PATCH 2/3] perf stat: Support per-die aggregation

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Date:   Tue, 28 May 2019 11:00:20 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     kan.liang@...ux.intel.com
Cc:     acme@...nel.org, jolsa@...nel.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        ak@...ux.intel.com
Subject: Re: [PATCH 2/3] perf stat: Support per-die aggregation

On Thu, May 23, 2019 at 01:41:20PM -0700, kan.liang@...ux.intel.com wrote:

SNIP

>  		if (cpu_map__build_core_map(evsel_list->cpus, &stat_config.aggr_map)) {
>  			perror("cannot build core map");
> @@ -936,21 +957,41 @@ static int perf_env__get_socket(struct cpu_map *map, int idx, void *data)
>  	return cpu == -1 ? -1 : env->cpu[cpu].socket_id;
>  }
>  
> +static int perf_env__get_die(struct cpu_map *map, int idx, void *data)
> +{
> +	struct perf_env *env = data;
> +	int die = -1, cpu = perf_env__get_cpu(env, map, idx);
> +
> +	if (cpu != -1) {
> +		/*
> +		 * Encode socket in upper 8 bits
> +		 * die_id is relative to socket,
> +		 * we need a global id. So we combine
> +		 * socket + die id
> +		 */
> +		die = (env->cpu[cpu].socket_id << 8) |
> +		      (env->cpu[cpu].die_id & 0xff);
> +	}
> +
> +	return die;
> +}
> +
>  static int perf_env__get_core(struct cpu_map *map, int idx, void *data)
>  {
>  	struct perf_env *env = data;
>  	int core = -1, cpu = perf_env__get_cpu(env, map, idx);
>  
>  	if (cpu != -1) {
> -		int socket_id = env->cpu[cpu].socket_id;
> -
>  		/*
> -		 * Encode socket in upper 16 bits
> -		 * core_id is relative to socket, and
> +		 * Encode socket in upper 24 bits
> +		 * encode die id in upper 16 bits
> +		 * core_id is relative to socket and die,
>  		 * we need a global id. So we combine
> -		 * socket + core id.
> +		 * socket + die id + core id
>  		 */
> -		core = (socket_id << 16) | (env->cpu[cpu].core_id & 0xffff);
> +		core = (env->cpu[cpu].socket_id << 24) |
> +		       (env->cpu[cpu].die_id << 16) |
> +		       (env->cpu[cpu].core_id & 0xffff);

I guess we're still safe with 1 byte for socket and die id,
but could we still check the size fits, and warn and bail
out otherwise?

thanks,
jirka