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"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? Whatever we do, time is pressing. - 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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