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On Friday 10 February 2006 18:17, Andrew Morton wrote: > "Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote: > > On Tue, Feb 07, 2006 at 03:36:17PM -0800, Andrew Morton wrote: > > > Suresh, Martin, Ingo, Nick and Con: please drop everything, > > > triple-check and test this: > > > > > > From: Peter Williams <pwil3058@bigpond.net.au> > > > > > > This is a modified version of Con Kolivas's patch to add "nice" support > > > to load balancing across physical CPUs on SMP systems. > > > > I have couple of issues with this patch. > > > > a) on a lightly loaded system, this will result in higher priority job > > hopping around from one processor to another processor.. This is because > > of the code in find_busiest_group() which assumes that SCHED_LOAD_SCALE > > represents a unit process load and with nice_to_bias calculations this is > > no longer true(in the presence of non nice-0 tasks) > > > > My testing showed that 178.galgel in SPECfp2000 is down by ~10% when run > > with nice -20 on a 4P(8-way with HT) system compared to a nice-0 run. > > > > b) On a lightly loaded system, this can result in HT scheduler > > optimizations being disabled in presence of low priority tasks... in this > > case, they(low priority ones) can end up running on the same package, > > even in the presence of other idle packages.. Though this is not as > > serious as "a" above... > > Thanks very much for discvoring those things. > > That rather leaves us in a pickle wrt 2.6.16. > > It looks like we back out smpnice after all? Give it the arse. > Whatever we do, time is pressing. We did without smp nice from 2.6.0 till 2.6.14, we can do without it again for some more time. Put it back in -mm for more tweaking and hopefully this added attention will get it more testing before being pushed. Cheers, 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/ | ||||||||||||
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