On 05/22/2015 11:55 AM, Brown, Len wrote:
>> +void set_base_cpu(void)
>> +{
>> + int cpu;
>> +
>> + for (cpu = 0; cpu <= topo.max_cpu_num; ++cpu) {
>> + if (cpu_is_not_present(cpu))
>> + continue;
>> + base_cpu = cpu;
>> + break;
>> + }
>> +
>> + if (base_cpu == -1)
>> + err(-ENODEV, "No valid cpus found");
>> +}
>
>
> cpu0 hard-coding is indeed arbitrary.
> However, so is this proposed replacement, base_cpu.
> Either may not match where turbostat is currently running,
> and thus could provoke unnecessary cross-calls to get there.
>
> I think it would be better to ask getcpu(2) where we are already running,
> and simply use that one. I think we can call it once and cache it,
> as you proposed, rather than multiple system calls.
Any objection to sched_getcpu()? That way the code is simply
base_cpu = sched_getcpu();
if (base_cpu == -1)
err(-ENODEV, "No valid cpus found");
P.
>
> thanks,
> -Len
>
> ps. patches to turbostat should go to linux...@vger.kernel.org
>
>
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