Re: [PATCH] O3int interactivity for 2.5.74-mm2

[Con Kolivas <kernel@kolivas.org>]

On Wed, 9 Jul 2003 01:12, Davide Libenzi wrote:
> On Tue, 8 Jul 2003, Con Kolivas wrote:
> > On Tue, 8 Jul 2003 17:46, Davide Libenzi wrote:
> > > On Tue, 8 Jul 2003, Szonyi Calin wrote:
> > > > In the weekend i did some experiments with the defines in
> > > > kernel/sched.c It seems that changing in MAX_TIMESLICE the "200" to
> > > > "100" or even "50" helps a little bit. (i was able to do a make
> > > > bzImage and watch a movie without noticing that is a kernel compile
> > > > in background)
> > >
> > > I bet it helps. Something around 100-120 should be fine. Now we need an
> > > exponential function of the priority to assign timeslices to try to
> > > maintain interactivity. This should work :
> >
> > This is still decreasing the timeslices. Whether you do it linearly or
> > exponentially the timeslices are smaller, which just about everyone will
> > resist you doing.
>
> Maybe you (and this Mr Everyone) might be interested in knowing that the
> interactivity is not given by the absolute length of the timeslice but by
> the ratio between timeslices. If you have three processes running with
> timeslices :
>
> A = 400
> B = 200
> C = 100
>
> the interactivity is the same of the one if you have :
>
> A = 100
> B = 50
> C = 25
>
> What changes is the maxiomum CPU blackout time that each task has to see
> before re-emerging again from the expired array. In the first case in
> "only" 700ms while in the first case is 175ms.

and what happens to the throughput?