Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Con Kolivas
2007-04-18T09:35:10Z

On Wednesday 18 April 2007 18:55, Nick Piggin wrote:
> On Tue, Apr 17, 2007 at 11:59:00AM +0200, Ingo Molnar wrote:
> > * Nick Piggin <npiggin@suse.de> wrote:
> > > 2.6.21-rc7-cfs-v2
> > > 534.80user 30.92system 2:23.64elapsed 393%CPU
> > > 534.75user 31.01system 2:23.70elapsed 393%CPU
> > > 534.66user 31.07system 2:23.76elapsed 393%CPU
> > > 534.56user 30.91system 2:23.76elapsed 393%CPU
> > > 534.66user 31.07system 2:23.67elapsed 393%CPU
> > > 535.43user 30.62system 2:23.72elapsed 393%CPU
> >
> > Thanks for testing this! Could you please try this also with:
> >
> > echo 100000000 > /proc/sys/kernel/sched_granularity
>
> 507.68user 31.87system 2:18.05elapsed 390%CPU
> 507.99user 31.93system 2:18.09elapsed 390%CPU
> 507.46user 31.78system 2:18.03elapsed 390%CPU
> 507.68user 31.93system 2:18.11elapsed 390%CPU
> 507.63user 31.98system 2:18.01elapsed 390%CPU
> 507.83user 31.94system 2:18.28elapsed 390%CPU
>
> > could you maybe even try a more extreme setting of:
> >
> > echo 500000000 > /proc/sys/kernel/sched_granularity
>
> 504.87user 32.13system 2:18.03elapsed 389%CPU
> 505.94user 32.29system 2:17.87elapsed 390%CPU
> 506.10user 31.90system 2:17.96elapsed 389%CPU
> 505.02user 32.02system 2:17.96elapsed 389%CPU
> 506.69user 31.96system 2:17.82elapsed 390%CPU
> 505.70user 31.84system 2:17.90elapsed 389%CPU
>
>
> Again, for comparison 2.6.21-rc7 mainline:
>
> 508.87user 32.47system 2:17.82elapsed 392%CPU
> 509.05user 32.25system 2:17.84elapsed 392%CPU
> 508.75user 32.26system 2:17.83elapsed 392%CPU
> 508.63user 32.17system 2:17.88elapsed 392%CPU
> 509.01user 32.26system 2:17.90elapsed 392%CPU
> 509.08user 32.20system 2:17.95elapsed 392%CPU
>
> So looking at elapsed time, a granularity of 100ms is just behind the
> mainline score. However it is using slightly less user time and
> slightly more idle time, which indicates that balancing might have got
> a bit less aggressive.
>
> But anyway, it conclusively shows the efficiency impact of such tiny
> timeslices.

See test.kernel.org for how (the now defunct) SD was performing on kernbench.
It had low latency _and_ equivalent throughput to mainline. Set the standard
appropriately on both counts please.

--
-ck