Re: [PATCH] 2.5.72 O(1) interactivity bugfix

[Con Kolivas <kernel@kolivas.org>]

On Thu, 19 Jun 2003 03:59, Andreas Boman wrote:
> On Wed, 2003-06-18 at 10:43, Con Kolivas wrote:
> > --BEGIN PGP SIGNED MESSAGE--
> > Hash: SHA1
> >
> > Hi Ingo, all
> >
> > While messing with the interactivity code I found what appears to be an
> > uninitialised variable (p->sleep_avg), which is responsible for all the
> > boost/penalty in the scheduler. Initialising this variable to 0 seems to
> > have made absolutely massive improvements to system responsiveness under
> > load and completely removed audio skips up to doing a make -j64 on my
> > uniprocessor P4 (beyond which swap starts being used), without changing
> > the scheduler timeslices. This seems to help all 2.4 O(1) based kernels
> > as well. Attached is a patch against 2.5.72 but I'm not sure about the
> > best place to initialise it.
>
> Applying this ontop of 2.5.72-mm1 causes more xmms/mpg321/ogg123
> skipping than with plain -mm1 here. make -j20 on my up athlon 1900+ with
> 512M ram causes extreme skipping until the make is killed. With plain
> -mm1 I may get _one_ skip at the very begining of a song during make
> -j20 (about 50% of the time). Plain -mm1 stops skipping after 10-15 sec
> of playback of a song, and even switching desktops after that doesnt
> cause skips, with or without make -j20 running (switching to/from
> desktops with apps like mozilla, evolution etc. will cause skips during
> the first 10-15 sec of a song regardless what I do it seems).
>
> Renicing xmms to -15 doesnt change anything with either kernel.

Hmm. I got too excited with the fact it improved so much on the 2.4 O(1) 
kernels that I didn't try it hard enough on the 2.5 kernels. I have had 
people quietly telling me that it isn't uninitialised, but that I am simply 
resetting it with this patch on new forked processes. It seems the extra 
changes to the 2.5 scheduler make this patch make things worse?

I need more testing of the 2.4 one as well to see if it was just my 
combination of hardware and kernel that was better with this...

Con