Re: [PATCH] reduce inter-node balancing frequency

[Nick Piggin]

Jesse Barnes wrote:
> On Thursday, July 15, 2004 8:14 pm, Martin J. Bligh wrote:
>
> > > Nick, we've had this patch floating around for awhile now and I'm
> > > wondering what you think.  It's needed to boot systems with lots (e.g.
> > > 256) nodes, but could probably be done another way.  Do you think we
> > > should create a scheduler domain for every 64 nodes or something?
> >
> > I think that'd make a lot of sense ...
>
>
> Yeah, though a smaller number of nodes would probably make more sense :)

Thirded :)

> > > Any other NUMA folks have thoughts about these values?
> >
> > Yeah, change them in arch specific code, not in the global stuff ;-)
>
>
> What, you mean we're the only ones with 256 nodes?

Yeah, these numbers actually used to be a lot higher, but someone
at Intel (I forget who it was right now) found them to be too high
on even a 32 way SMT system. They could probably be raised a *little*
bit in the generic code.

> > But seeing as they're dependant (for you) on machine size, as well as
> > arch type, you probably need to do something cleverer in
> > arch_init_sched_domain
>
>
> Ok, I'll check that out.
>
>
> > But the big bugaboo is arch-specific vs general ... we need to break
> > opteron vs i386 vs ia64 out from each other ... they all need different
> > coefficients.
> >
> > If you were going to be really fancy, we could do it in common code off
> > the topology stuff ... but for now, I think it's easier to just set 'em
> > per arch ...
>
>
> We may have enough information to do that already... I'll look.

The plan is to allow arch overridable SD_CPU/NODE_INIT macros for
those architectures that just look like a regular SMT+SMP+NUMA, and
have the generic code set them up.
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