Re: 2.6.12-rc2-mm1

Nick Piggin
2005-04-08T02:29:04Z

On Thu, 2005-04-07 at 18:08 -0700, Siddha, Suresh B wrote:
> On Thu, Apr 07, 2005 at 03:11:12AM +1000, Nick Piggin wrote:
> > Using the attached patch, a puny dual PIII-650 with ~400MB RAM swapped
> > itself to death after 20000 infinite loop tasks had been pinned to one
> > of the CPUs. See how you go.
>
> Its goes well beyond the initial 7000 number I mentioned. Thanks.
>

OK, good thanks for testing that. I'll send it to Andrew.

> One side-effect of this patch is: for example we have only two processes
> running on a cpu and both are pinned to that cpu. If someone comes and
> changes the affinity of one of these processes to all cpu's in the system,
> then it might take MAX_PINNED_INTERVAL before this process moves to an idle cpu.
>

Yeah, that is true. OTOH it is a bit of a special case, and our
multiprocessor scheduling in general practically shuts down when
we have a situation with a single queue with a lot of pinned tasks.

What did I have for MAX_PINNED_INTERVAL? ~1second. I guess that could
come down a bit - maybe 1/4 or 1/2 a second? I think it is a "good
enough for now" kind of situation.

--
SUSE Labs, Novell Inc.