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SubjectRe: oltp ~10% regression with 2.6.27-rc5 on stoakley machine
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> > > 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? :-)
>



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