Messages in this thread | | | Date | Wed, 15 Nov 2017 09:47:11 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] x86: use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz" again |
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On Tue, 14 Nov 2017, Linus Torvalds wrote: > On Tue, Nov 14, 2017 at 3:53 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > Current head + Raphaels patch: > > > > real 0m0.029s > > user 0m0.000s > > sys 0m0.010s > > > > So that patch is actually slower. > > Oh it definitely is expected to be slower, because it does the IPI to > all the cores and actually gets their frequency right. > > It was the old one that we had to revert (because it did so > sequentially) that was really bad, and took something like 2+ seconds > on Ingo's 160-core thing, iirc. >
Tired brain did not connect it to the revert.
On that machine with ea0ee3398877: Revert "x86: CPU: Fix up "cpu MHz" in /proc/cpuinfo" reverted it takes:
real 0m4.497s user 0m0.012s sys 0m0.000s
> It sounds like the current patch is slower, but likely acceptable > considering that you get the right results now ..
Correct and the factor 10, i.e. 30ms vs. 3ms is not horrible, while the 4.5 seconds are.
Thanks,
tglx
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