Re: [Lse-tech] [patch] sched-domain cleanups, sched-2.6.5-rc2-mm2-A3

Andi Kleen
2004-03-29T08:46:03Z

On Thu, Mar 25, 2004 at 09:30:32PM +0100, Ingo Molnar wrote:
>
> * Andi Kleen <ak@suse.de> wrote:
>
> > That won't help for threaded programs that use clone(). OpenMP is such
> > a case.
>
> this patch:
>
> redhat.com/~mingo/scheduler-patches/sched-2.6.5-rc2-mm3-A4
>
> does balancing at wake_up_forked_process()-time.
>
> but it's a hard issue. Especially after fork() we do have a fair amount
> of cache context, and migrating at this point can be bad for
> performance.

I ported it by hand to the -mm4 scheduler now and tested it. While
it works marginally better than the standard -mm scheduler
(you get 1 1/2 the bandwidth of one CPU instead of one) it's still
still much worse than the optimum of nearly 4 CPUs archived by
2.4 or the standard scheduler.

-Andi