Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods

Li, Aubrey
2017-07-10T13:59:46Z

On 2017/7/10 16:46, Peter Zijlstra wrote:
> On Mon, Jul 10, 2017 at 09:38:30AM +0800, Aubrey Li wrote:
>> We measured 3%~5% improvemnt in disk IO workload, and 8%~20% improvement in
>> network workload.
>
> Argh, what a mess :/
>
> So how much of the gain is simply due to skipping NOHZ?

netperf reports 6~7% improvement due to skipping NOHZ, but still have 2~3%
improvement due to excluding RCU idle enter/exit, c-state selection and other
deferrable items. Also a shallow HW c-state is used in the idle loop, which
means faster HW sleep enter and exit.

> Mike used to carry a patch that would throttle NOHZ. And that is a _far_ small
> and simpler patch to do.
>
Can you please point me to the link of Mike's patch?

Thanks,
-Aubrey