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Date: Thu, 04 Sep 2008 20:12:08 +0800 From: Lin Ming <ming.m.lin@...el.com> To: Peter Zijlstra <a.p.zijlstra@...llo.nl> Cc: linux-kernel <linux-kernel@...r.kernel.org>, "Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>, mingo <mingo@...e.hu>, Gregory Haskins <ghaskins@...ell.com> Subject: Re: oltp ~10% regression with 2.6.27-rc5 on stoakley machine > > > Thats bizarre... that just indicates the better clock, which should give > > > better (read fairer) scheduling hurts your workload. > > > > > > Is there anything I can run to see if we can fix the scheduler perhaps? > > > > I observed schedstats of sysbench, there's more > > "nr_failed_migrations_hot" > > > > 2.6.27-rc4: se.nr_failed_migrations_hot 11 > > 2.6.27-rc5: se.nr_failed_migrations_hot 95 > > > > task migration failed because of task_hot, the system is un-balanced? > > Ah, that makes sense, a more accurate clock could indeed make more tasks > hot. > > Can you try fiddling with: /proc/sys/kernel/sched_migration_cost ? sched_migration_cost regression ---------------------- ------------- 50000 ~6% 0 ~8% 500000 (default) ~10% 5000000 ~14% -1 ~19% > > Also, we used to have some auto-tuning in there, which dissapeared some > time ago, gregory brought it back to live recently, perhaps he likes to > share? :-) > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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