Messages in this thread | | | Date | Mon, 1 Feb 2016 13:36:22 -0800 | From | Andi Kleen <> | Subject | Re: [PATCH] Optimize int_sqrt for small values for faster idle |
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On Mon, Feb 01, 2016 at 10:25:17PM +0100, Rasmus Villemoes wrote: > On Thu, Jan 28 2016, Andi Kleen <andi@firstfloor.org> wrote: > > > From: Andi Kleen <ak@linux.intel.com> > > > > The menu cpuidle governor does at least two int_sqrt() each time > > we go into idle in get_typical_interval to compute stddev > > > > int_sqrts take 100-120 cycles each. Short idle latency is important > > for many workloads. > > > > If you want to optimize get_typical_interval(), why not just take the > square root out of the equation (literally)? > > Something like
Looks good. Yes that's a better fix.
-Andi
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