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?
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