lkml.org 
[lkml]   [2008]   [Jan]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Performance loss 2.6.22->22.6.23->2.6.24-rc7 on CPU intensive benchmark on 8 Core Xeon

* Colin Fowler <elethiomel@gmail.com> wrote:

> > there are a handful of 'scheduler feature bits' in
> > /proc/sys/kernel/sched_features:
> >
> > enum {
> > SCHED_FEAT_NEW_FAIR_SLEEPERS = 1,
> > SCHED_FEAT_WAKEUP_PREEMPT = 2,
> > SCHED_FEAT_START_DEBIT = 4,
> > SCHED_FEAT_TREE_AVG = 8,
> > SCHED_FEAT_APPROX_AVG = 16,
> > };
> >
>
> Toggling SCHED_FEAT_NEW_FAIR_SLEEPERS to 0 or
> SCHED_FEAT_WAKEUP_PREEMPT to 0 gives me results more inline with my
> 2.6.22 results. Toggling them both to 0 gives me slightly better
> results than 2.6.22!

ok, but it would be nice to avoid having to turn these off. Could you
try whether tuning the /proc/sys/kernel/*granularity* values (in
particular wakeup_granularity) has any positive effect on your workload?

also, could you run your workload as SCHED_BATCH [via schedtool -B ],
does that improve the results as well on a default-tuned kernel?

Ingo


\
 
 \ /
  Last update: 2008-01-18 11:59    [W:0.095 / U:1.536 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site