Re: 2.6.4-mm1

Andrew Morton
2004-03-11T19:34:38Z

Andi Kleen <ak@muc.de> wrote:
>
> Andrew Morton <akpm@osdl.org> writes:
>
> > - The CPU scheduler changes in -mm (sched-domains) have been hanging about
> > for too long. I had been hoping that the people who care about SMT and
> > NUMA performance would have some results by now but all seems to be silent.
> >
> > I do not wish to merge these up until the big-iron guys can say that they
> > suit their requirements, with a reasonable expectation that we will not
> > need to churn this code later in the 2.6 series.
> >
> > So. If you have been testing, please speak up. If you have not been
> > testing, please do so.
>
> I tested them on Opteron NUMA systems and they are worse on simple
> tests than the stock scheduler (e.g. the parallelized STREAM test,
> which is a bit silly, but still fairly important)

OK, thanks.

> For SMT there is a patch from Intel pending that teaches x86-64
> to set up the SMT scheduler. They said they got slightly better
> benchmark results. The SMT setup seems to be racy though.

Am I correct in thinking that this patch provides the necessary hooks to
integrate x86_4 into the new functionality which sched-domains provides, or
is the Intel patch independent of sched-domains?

> Some kind of SMT scheduler is definitely needed, we have a serious
> regression compared to 2.4 here right now. I'm not sure this
> is the right approach though, it seems to be far too complex.

Well that's discouraging. I really do want to push this thing along a bit.

Yours is the only report of regression of which I am aware. Is the reason
understood?

And is anyone developing alternative SMT enhancements?