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

From: Arjan van de Ven
Date: Fri Jul 14 2017 - 11:52:35 EST

On 7/14/2017 8:38 AM, Peter Zijlstra wrote:
No, that's wrong. We want to fix the normal C state selection process to
pick the right C state.

The fast-idle criteria could cut off a whole bunch of available C
states. We need to understand why our current C state pick is wrong and
amend the algorithm to do better. Not just bolt something on the side.

I can see a fast path through selection if you know the upper bound of any
selection is just 1 state.

But also, how much of this is about "C1 be fast" versus "selecting C1 is slow"

a lot of the patches in the thread seem to be about making a lighter/faster C1,
which is reasonable (you can even argue we might end up with 2 C1s, one fast
one full feature)