Messages in this thread | | | Date | Fri, 18 Jan 2008 11:55:45 +0100 | From | Ingo Molnar <> | Subject | Re: Performance loss 2.6.22->22.6.23->2.6.24-rc7 on CPU intensive benchmark on 8 Core Xeon |
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* 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
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