Re: [PATCH][resubmit] x86: enable preemption in delay

Nick Piggin
2008-06-18T12:43:29Z

On Wednesday 18 June 2008 22:25, Gregory Haskins wrote:
> >>> On Wed, Jun 18, 2008 at 8:16 AM, in message

> > Yeah - migrate_disable() has been proposed several times. The reason I
> > don't like it is that is creates scheduling artefacts like latencies by
> > not being able to load-balance (and thereby complicates all that, and
> > you know we don't need more complication there).
>
> True, and good point. But this concept would certainly be useful to avoid
> the heavyweight (w.r.t. latency) preempt-disable() in quite a few different
> areas, so if we can make it work with reasonable visibility, it might be
> nice to have.

It just seems like pretty worthless bloat to me.

There are _some_ cases where it can be used, but nobody has been
able to come up with compelling uses really. I don't think this
case is helped very much either because the logic in there using
preempt-disable is fine, isn't it?

Except that it should also have a cond_resched in it. Seems like
an ideal place to put cond_resched because it is not a fastpath.