Re: [PATCH] 2.6.0 batch scheduling, HT aware

From: Con Kolivas (kernel_at_kolivas.org)
Date: 12/23/03

  • Next message: Rusty Russell: "Re: [PATCH] another minor bit of cpumask cleanup" 
    To: Nick Piggin <piggin@cyberone.com.au>
Date:	Tue, 23 Dec 2003 13:42:56 +1100

    On Tue, 23 Dec 2003 12:36, Nick Piggin wrote:
    > Con Kolivas wrote:
    > >On Tue, 23 Dec 2003 12:11, Nick Piggin wrote:
    > >>I think this patch is much too ugly to get into such an elegant
    > >> scheduler. No fault to you Con because its an ugly problem.
    > >
    > >You're too kind. No it's ugly because of my code but it works for now.
    >
    > Well its all the special cases for batch scheduling that I don't like,
    > the idea to not run batch tasks on a package running non batch processes
    > is sound. I thought the batch scheduling code is Ingo's, but I could
    > be mistaken. Anyway...

    I realise the special cases suck. Code for one setting in a spot where it
    affects everyone is bad. Regarding the batch scheduling; no that's my special
    flavour coded ugly from the ground up. Ingo's is much smarter than this but
    once again I needed something that works now without too much effort.

    >
    > >>How about this: if a task is "delta" priority points below a task running
    > >>on another sibling, move it to that sibling (so priorities via timeslice
    > >>start working). I call it active unbalancing! I might be able to make it
    > >>fit if there is interest. Other suggestions?
    > >
    > >I discussed this with Ingo and that's the sort of thing we thought of.
    > > Perhaps a relative crossover of 10 dynamic priorities and an absolute
    > > crossover of 5 static priorities before things got queued together. This
    > > is really only required for the UP HT case.
    >
    > Well I guess it would still be nice for "SMP HT" as well. Hopefully the
    > code can be generic enough that it would just carry over nicely.

    I disagree. I can't think of a real world scenario where 2+ physical cpus
    would benefit from this.

    > It does
    > have complications though because the load balancer would have to be taught
    > about it, and those architectures that do hardware priorities probably
    > don't even want it.

    Probably the simple relative/absolute will have to suffice. However it still
    doesn't help the fact that running something cpu bound concurrently at nice 0
    with something interactive nice 0 is actually slower if you use a UP HT
    processor in SMP mode instead of UP.

    Con

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  • Next message: Rusty Russell: "Re: [PATCH] another minor bit of cpumask cleanup"