Re: Question about fair schedulers

[Bill Davidsen <davidsen@tmr.com>]

Alberto Gonzalez wrote:
> On Saturday 23 June 2007, Tom Spink wrote:
> > Alberto,
> >
> > If you're feeling adventurous, grab the latest kernel and patch it
> > with Ingo's scheduler: CFS.
> >
> > You may be pleasantly surprised.
>
> Thanks, I might if I have to courage to patch and compile my own kernel :)
>
> However, I'd also need to change all my applications to set them with the 
> right priority to see the good results, so I think I might just wait until it 
> lands in mainline.

In general not the case. I generally don't diddle my priorities, there's 
rarely a need.
> Just to check if I understood everything correctly:
>
> The mainline scheduler tries to be smart and guess the priority of each task, 
> and while it mostly hits the nail right in the head, sometimes it hits you 
> right in the thumb.
>
> Fair schedulers, on the contrary, forget about trying to be smart and just 
> care about being fair, leaving the priority settings to where they belong: 
> applications.
>
> Is this more or less correct?

Incomplete. The CFS scheduler seems to do better with latency, so you 
may get less CPU to a process but it doesn't wind up waiting a long time 
to get a fair share. So it "feels better" without micro tuning.

Face it, if you have more jobs than CPU no scheduler is going to make 
you really happy.
> Alberto.


--
Bill Davidsen <davidsen@tmr.com>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/