Re: [RFT][PATCH v7 5/8] cpuidle: Return nohz hint from cpuidle_select()

Thomas Ilsche
2018-03-21T18:01:05Z

On 2018-03-21 15:36, Rafael J. Wysocki wrote:
>
> So please disregard this one entirely and take the v7.2 replacement
> instead of it:https://patchwork.kernel.org/patch/10299429/
>
> The current versions (including the above) is in the git branch at
>
> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \
> idle-loop-v7.2

With v7.2 (tested on SKL-SP from git) I see similar behavior in idle
as with v5: several cores which just keep the sched tick enabled.
Worse yet, some go only in C1 (not even C1E!?) despite sleeping the
full sched tick.
The resulting power consumption is ~105 W instead of ~ 70 W.

https://wwwpub.zih.tu-dresden.de/~tilsche/powernightmares/v7_2_skl_sp_idle.png

I have briefly ran v7 and I believe it was also affected.