On Thu, 2008-09-04 at 20:12 +0800, Lin Ming wrote:
quoted text
> > > > 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%

at 50000 (~6%), is the predominant difference in schedstats still the
nr_failed_migrations_hot?

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