Subject: Re: [PATCH repost] sched: export sched_set/getaffinity to modules

From: Peter Zijlstra <[email-masked]>
Date: Thu, 01 Jul 2010 13:43:23 +0200

On Thu, 2010-07-01 at 13:19 +0200, Peter Zijlstra wrote:
> On Thu, 2010-07-01 at 14:07 +0300, Michael S. Tsirkin wrote:
> > Author: Sridhar Samudrala <[email-masked]>
> > 
> > sched: export sched_set/getaffinity to modules
> > 
> > vhost-net driver wants to copy the affinity from the
> > owner thread to thread it creates. Export
> > sched_set/get affinity to modules to make this possible
> > when vhost is built as a module.

> Urgh,.. so why again is that a good idea?

In particular:
 - who sets the affinity of the task? 
 - why can't it set the kernel thread's affinity too?
 - what happens if someone changes the tasks' affinity?

So no, I don't think this is a sensible thing to do at all.