2017-11-16 20:37:38

by Thomas Ilsche

[permalink] [raw]
Subject: Re: [PATCH] cpuidle: Add "cpuidle.use_deepest" to bypass governor and allow HW to go deep

On 2017-11-09 08:38, Len Brown wrote:
> From: Len Brown <[email protected]>
>
> While there are several mechanisms (cmdline, sysfs, PM_QOS) to limit
> cpuidle to shallow idle states, there is no simple mechanism
> to give the hardware permission to enter the deeptest state permitted by PM_QOS.
>
> Here we create the "cpuidle.use_deepest" modparam to provide this capability.
>
> "cpuidle.use_deepest=Y" can be set at boot-time, and
> /sys/module/cpuidle/use_deepest can be modified (with Y/N) at run-time.

This is a good option to have and can conveniently prevent idle power consumption
issues. But that wouldn't be a reasonable default, would it?
I still think there is an inherent need for a heuristic and a corresponding
mitigation to avoid staying in a sleep state too long.

Best,
Thomas


From 1583700433273808768@xxx Fri Nov 10 17:20:28 +0000 2017
X-GM-THRID: 1583573317012724483
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread