Messages in this thread | | | Date | Thu, 30 Sep 2004 22:45:02 +0200 | From | Andi Kleen <> | Subject | Re: [RFC PATCH] sched_domains: Make SD_NODE_INIT per-arch |
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On Thu, Sep 30, 2004 at 11:36:52AM -0700, Matthew Dobson wrote: > On Thu, 2004-09-30 at 01:15, Nick Piggin wrote: > > Matthew Dobson wrote: > > > IA64 already has their own version of SD_NODE_INIT, tuned for their > > > extremely large machines. I think that all arches would benefit from > > > having their own, arch-specific SD_NODE_INIT initializer, rather than > > > the one-size-fits-all variant we've got now. > > > > > > > I suppose the patch is pretty good (IIRC Martin liked the idea). > > I guess it will at least increase the incidence of copy+paste, > > if not getting people to think harder ;) > > Thanks! Martin does like the idea, and I think Andi Kleen likes the > idea of being able to tune sched_domains for x86_64, too. Any comments, > Andi?
It doesn't help me directly - what i need is the same thing for SD_SIBLING_INIT for the CMP changes.
But it seems I need to do some other work to properly support the K8 CMP first, so I'm defering attacking this a bit.
> The patch is pretty simple. I don't think it will increase any > copy+pasting because I don't believe anyone has modified SD_NODE_INIT at > all since it's been implemented, and certainly not for many kernel > releases. I think part of the reason for that is that it is currently > impossible to tweak the values for your architecture of choice because > modifying the values now will change EVERYONE's sched_domains timings. > Which is bad. :( If anyone wants to tweak SD_NODE_INIT, they shouldn't > be copying+pasting those values to all architectures. Besides, IA64 > already gets their own SD_NODE_INIT to play with, why shouldn't everyone > else! ;)
It would be nice if there was a SD_DEFAULT_NODE_INIT and a SD_DEFAULT_SIBLING_INIT in some generic file that architecture code can use as a base for tweaking. For the CMP change I currently only want to remove SD_SHAREPOWER from SIBLING_INIT to get rid of SMT nice.
Later we'll probably want a SD_DEFAULT_CMP_INIT too that gives generic values for a dual core. Dual cores should be soon pretty common and tuning for them will be needed on several architectures (ppc64, ia64, x86, x86-64, sparc, parisc? ...). But figuring out good values for this will require a lot of benchmarking first.
-Andi
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