On Fri, Dec 13, 2019 at 8:14 AM Laura Abbott <labbott@xxxxxxxxxx> wrote: > > On 12/12/19 9:10 AM, Justin Forbes wrote: > > On Thu, Dec 12, 2019 at 3:48 AM Peter Robinson <pbrobinson@xxxxxxxxx> wrote: > >> > >> Hey All. > >> > >> In digging through some pieces around CPU_IDLE I noticed that > >> NO_HZ_IDLE is explicitly disabled on x86_64 but not on all other > >> architectures. > >> > >> Doing a "git log --follow > >> configs/fedora/generic/x86/x86_64/CONFIG_NO_HZ_IDLE" it goes all the > >> way back to 2016 when we changed the way the configs were handled. > >> > >> The upstream kernel's opinion [1] on it is "Most of the time you want > >> to say Y here." so I'm wondering if there's a reason why we're > >> difference on x86_64 or is it just lost in the winds of time? > >> > >> Peter > >> > >> PS was digging around CPU_IDLE_GOV_TEO for those curious. > >> > >> [1] https://cateee.net/lkddb/web-lkddb/NO_HZ_IDLE.html > > > > > > commit 3836faf6e68495fc70316229a3540506f7ce4c98 > > Author: Kyle McMartin <kyle@xxxxxxxxxxxxxxxxx> > > Date: Wed Sep 17 13:10:12 2014 -0500 > > > > re-enable RCU_FAST_NO_HZ, enable NO_HZ_FULL on x86_64 > > > > - I also like to live dangerously. (Re-enable RCU_FAST_NO_HZ which > > has been off > > since April 2012. Also enable NO_HZ_FULL on x86_64.) > > Yeah I wouldn't quite say it's been "lost" but the real question > is if it still makes sense. I don't have a strong opinion without > data. Prarit, any opinion here? Oh, I wasn't pointing out that it wasn't just lost, I was pointing out that NO_HZ_IDLE is not set because we run NO_HZ_FULL. We were one of the first distros to do so, and it has worked well for us. I have a fairly strong opinion about not dropping back to IDLE without good reason. _______________________________________________ kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/kernel@xxxxxxxxxxxxxxxxxxxxxxx
