Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 14 Nov 2017 16:06:12 -0800 | Subject | Re: [PATCH] x86: use cpufreq_quick_get() for /proc/cpuinfo "cpu MHz" again |
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On Tue, Nov 14, 2017 at 4:04 PM, Linus Torvalds <torvalds@linux-foundation.org> 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.
Looked it up. Ingo's machine "only" had 120 cores, and he said
fomalhaut:~> time cat /proc/cpuinfo >/dev/null real 0m2.689s
for the bad serial case, so yeah, it looks "a bit" better than it was ;)
Linus
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