linux-kernel - Re: [PATCH] perf: fix topology test on systems with sparse CPUs

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Date:   Mon, 30 Jan 2017 19:49:22 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jan Stancek <jstancek@...hat.com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, acme@...nel.org,
        alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
        mhiramat@...nel.org, rui.teng@...ux.vnet.ibm.com,
        sukadev@...ux.vnet.ibm.com
Subject: Re: [PATCH] perf: fix topology test on systems with sparse CPUs

On Mon, Jan 30, 2017 at 05:53:34PM +0100, Jan Stancek wrote:

SNIP

> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
> index bb964e86b09d..0c2cae807a61 100644
> --- a/tools/perf/util/env.c
> +++ b/tools/perf/util/env.c
> @@ -60,29 +60,45 @@ int perf_env__set_cmdline(struct perf_env *env, int argc, const char *argv[])
>  
>  int perf_env__read_cpu_topology_map(struct perf_env *env)
>  {
> -	int cpu, nr_cpus;
> +	int cpu, nr_cpus, i, err = 0;
> +	struct cpu_map *map;
>  
>  	if (env->cpu != NULL)
>  		return 0;
>  
> -	if (env->nr_cpus_avail == 0)
> -		env->nr_cpus_avail = sysconf(_SC_NPROCESSORS_CONF);
> +	map = cpu_map__new(NULL);

could you please put comment in here, explaining that
cpu_map__new(NULL) makes map with current online cpus

thanks,
jirka