lkml.org 
[lkml]   [2013]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] mm: call cond_resched() per MAX_ORDER_NR_PAGES pages copy
On Mon, Nov 18, 2013 at 02:29:24PM -0800, Dave Hansen wrote:
> On 11/18/2013 01:56 PM, Naoya Horiguchi wrote:
> >> > Why bother trying to "optimize" it?
> > I thought that if we call cond_resched() too often, the copying thread can
> > take too long in a heavy load system, because the copying thread always
> > yields the CPU in every loop.
>
> I think you're confusing cond_resched() and yield(). The way I look at it:
>
> yield() means: "Hey scheduler, go right now and run something else I'm
> done running"
>
> cond_resched() means: "Schedule me off if the scheduler has already
> decided something else _should_ be running"
>
> I'm sure I'm missing some of the subtleties, but as I see it, yield()
> actively goes off and finds something else to run. cond_resched() only
> schedules you off if you've *already* run too long.

I see.
Thanks for the explanation!

Naoya


\
 
 \ /
  Last update: 2013-11-19 02:21    [W:0.089 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site