Re: [announce] CFS-devel, performance improvements

Ingo Molnar
2007-09-13T09:31:55Z

* Rob Hussey <robjhussey@gmail.com> wrote:

> On 9/13/07, Ingo Molnar <mingo@elte.hu> wrote:
> >
> > thanks for the numbers! Could you please also post the .config you used?
>
> Sure, .config for 2.6.23-rc1 and 2.6.23-rc6 attached.

thx! If you've got some time, could you perhaps re-measure with these
disabled:

CONFIG_SCHED_DEBUG=y
CONFIG_SCHEDSTATS=y

these options mask some of the performance enhancements we made. There's
also a new code drop at:

http://people.redhat.com/mingo/cfs-scheduler/devel/

with some fixes for SMP. (and you've got an SMP box it appears)

also, if you want to maximize performance, it usually makes more sense
to build with these flipped around:

# CONFIG_CC_OPTIMIZE_FOR_SIZE is not set
CONFIG_FORCED_INLINING=y

i.e.:

CONFIG_CC_OPTIMIZE_FOR_SIZE=y
# CONFIG_FORCED_INLINING is not set

because especially on modern x86 CPUs, smaller x86 code is faster. (and
it also takes up less I-cache size)

Ingo