On 12/12/19 9:10 AM, Justin Forbes wrote:
On Thu, Dec 12, 2019 at 3:48 AM Peter Robinson
<pbrobinson(a)gmail.com> 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(a)fedoraproject.org>
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?