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Re: Poor condvar performance



On Wed, 2003-11-26 at 17:05, Ulrich Drepper wrote:
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> Ingo Molnar wrote:
> 
> > it turns out that the requeue implementation had to be turned off in the
> > CVS a few weeks ago
> 
> Not entirely, only for cond_signal.  cond_broadcast still uses requeue
> for condvars without pshared.  I don't see how, if requeue works, using
> cond_broadcast could create a scheduling storm.  There must be some
> other factors involved.
> 
> - -- 
> â?§ Ulrich Drepper â?§ Red Hat, Inc. â?§ 444 Castro St â?§ Mountain View, CA â??
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Ah, I am using pshared cond vars (hence why I needed the recent fix).
What is the plan for putting back the requeue for pshared? (I'm happy to
stay with the futex / sched hack for now, but as a matter of interest).

Incidentally, using cond_signal() I see around 300000 content switches /
sec and with broadcast, 200000 / sec.

Thanks

Luke.





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