Peter Zijlstra's on April 25, 2019 9:56 pm: > On Fri, Apr 12, 2019 at 02:26:13PM +1000, Nicholas Piggin wrote: >> The nohz idle balancer runs on the lowest idle CPU. This can >> interfere with isolated CPUs, so confine it to HK_FLAG_MISC >> housekeeping CPUs. >> >> HK_FLAG_SCHED is not used for this because it is not set anywhere >> at the moment. This could be folded into HK_FLAG_SCHED once that >> option is fixed. > > Frederic? Anyway, I thnk I'll take this patch as is.
That would be great, thanks. We've been testing it in a staging environment (this is where they noticed the noise in the first place), and results have been as expected: I've been able to test Nick's idle-loop load balancer (ILB) patch, with and without the TEO cpuidle governor. With the ILB patch (and nohz_full) I get a very quiet noise profile with either cpuidle governor (menu or teo). For my tests, I don't see a meaningful difference between the two governors. [...] Bottom line: Nick's patch that constrains the ILB to run on non-nohz cores has a noticeable noise-reduction effect. For this type of workload, the choice of cpuidle governor, menu or teo, is immaterial. This is against a slightly backported RHEL kernel they are using, but no significant differences from upstream in these areas. Thanks, Nick
