lkml.org 
[lkml]   [2013]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: power-efficient scheduling design
On 6/11/2013 5:27 PM, David Lang wrote:
>
> Nobody is saying that this sort of thing should be in the fastpath of the scheduler.
>
> But if the scheduler has a table that tells it the possible states, and the cost to get from the current state to each of these states (and to get back and/or wake up to
> full power), then the scheduler can make the decision on what to do, invoke a routine to make the change (and in the meantime, not be fighting the change by trying to
> schedule processes on a core that's about to be powered off), and then when the change happens, the scheduler will have a new version of the table of possible states and costs
>
> This isn't in the fastpath, it's in the rebalancing logic.

the reality is much more complex unfortunately.
C and P states hang together tightly, and even C state on
one core impacts other cores' performance, just like P state selection
on one core impacts other cores.

(at least for x86, we should really stop talking as if the OS picks the "frequency",
that's just not the case anymore)



\
 
 \ /
  Last update: 2013-06-12 04:21    [W:0.317 / U:0.476 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site