Re: [PATCH v2] cpuidle: poll_state: Add time limit to poll_idle()

Peter Zijlstra
2018-03-22T19:11:46Z

On Thu, Mar 22, 2018 at 12:32:18PM -0400, Rik van Riel wrote:
> On Wed, 2018-03-14 at 13:04 +0100, Peter Zijlstra wrote:
>
> > On x86 we don't have to use that time_check_counter thing,
> > sched_clock()
> > is really cheap, not sure if it makes sense on other platforms.
>
> Are you sure? I saw a 5-10% increase in CPU use,
> for a constant query rate to a memcache style
> workload, with v3 of this patch.

Well, I expected it to be really cheap, but if you have numbers saying
otherwise, clearly I'll need to adjust expectations ;-)