Messages in this thread | | | Date | Fri, 22 May 2015 18:30:18 -0400 | From | Prarit Bhargava <> | Subject | Re: [PATCH 2/2] turbostat, add set_base_cpu() |
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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-pm@vger.kernel.org > >
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