On Mon, Feb 01 2016, Andi Kleen <a...@linux.intel.com> wrote: > On Mon, Feb 01, 2016 at 10:25:17PM +0100, Rasmus Villemoes wrote: >> On Thu, Jan 28 2016, Andi Kleen <a...@firstfloor.org> wrote: >> >> > From: Andi Kleen <a...@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, did you have a way to measure the impact, and if so, could I get you to run the numbers again with my patch? Thanks, Rasmus
