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

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Date:   Mon, 30 Jan 2017 19:49:08 +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

> +		ret = build_cpu_topo(tp, cpu);
>  		if (ret < 0)
>  			break;
>  	}
> +
> +out_free:
> +	cpu_map__put(map);
>  	if (ret) {
>  		free_cpu_topo(tp);
>  		tp = NULL;
>  	}
> +out:
>  	return tp;
>  }
>  
> @@ -575,7 +579,7 @@ static int write_cpu_topology(int fd, struct perf_header *h __maybe_unused,
>  	if (ret < 0)
>  		goto done;
>  
> -	for (j = 0; j < perf_env.nr_cpus_avail; j++) {
> +	for (j = 0; j < perf_env.nr_cpus_online; j++) {

so basically we're changing from avail to online cpus

have you checked all the users of this FEATURE
if such change is ok?

I can't find any after quick search, but it would be
good to be sure and mention that in changelog

thanks,
jirka