Re: [PATCH] set_cpus_allowed() for 2.4

Andrea Arcangeli (andrea@suse.de)
Wed, 4 Dec 2002 02:21:44 +0100


On Tue, Dec 03, 2002 at 05:14:40PM -0800, Andrew Morton wrote:
> Andrea Arcangeli wrote:
> >
> > On Tue, Dec 03, 2002 at 04:30:28PM -0800, Andrew Morton wrote:
> > > load is just one or more busywaits. It has to be a compilation. It
> > > could be something to do with all the short-lived processes, or gcc -pipe)
> >
> > could be that we think they're very interactive or something like that.
>
> I just retested. This is on uniprocessor. Running `make -j1 bzImage',
> while typing into a StarOffice 5.2 document:
>
> - 2.4.19-pre4: smooth
> - 2.4.20aa1: Jerky. Sometimes it's OK, sometimes a few characters
> lag.
>
> Then I disabled `-pipe' in the build and restarted it:
>
> - 2.4.19-pre4: smooth
> - 2.4.20aa1: Quite a lot more jerky. Enough to be a bit irritating.
>
> > ...
> > >
> > > This problem is the "changed sched_yield semantics". It was actually
> > > tested on uniprocessor. The difference between 2.4 and 2.4-aa is
> > > still noticeable here, but it is not a terrible problem now.
> >
> > strange, the algorithm should be nearly the same now (modulo RT). Still
> > I wonder that's something else on the short lived gcc processes side.
>
> Could be. Removing -pipe affected it quite a bit.

you could try decreasing PARENT_PENALTY to 50. I would like to see if
the scheduler *still* thinks they're interactive stuff then.

Andrea
-
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/