Re: scheduling

Alexander Kjeldaas (astor@guardian.no)
Fri, 1 May 1998 22:09:39 +0200

On Fri, May 01, 1998 at 09:42:44PM +0200, Rik van Riel wrote:
> On Fri, 1 May 1998, Alexander Kjeldaas wrote:
>
> > processes. However, I was not aware of any recent sched_yield() fixes
> > [it was not fixed in 2.1.90 it seems], nor that the recalculations are
> > less frequent when the number of processes grow. Considering 2000
> > processes, that makes for a recalculation fewer than once per 6
> > minutes.
>
> That happens only when you actually have 6000 _running_
> processes, in which case no calculation can save
> performance :-)
>

Sorry, I misread mingo's posting, my error! But this means that with
2000 processes, assuming the run queue has 1 entry (as mingo points
out), we will recalculate 5 times/second on i386. Each time we will
use 1ms which means we use 0.5% cpu in the scheduler. This is on a
very fast computer (pII/300MHz). On an alpha, it could easily be 5%
since it does 10x as many schedule() calls. Are there any numbers on
this?

astor

-- 
 Alexander Kjeldaas, Guardian Networks AS, Trondheim, Norway
 http://www.guardian.no/


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