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SubjectRE: [PATCH 2/2] turbostat, add set_base_cpu()
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> +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.

thanks,
-Len

ps. patches to turbostat should go to linux-pm@vger.kernel.org




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