pthread switch (was Odd KSE panic)
julian at elischer.org
Tue Jul 6 14:22:24 PDT 2004
On Tue, 6 Jul 2004, Daniel Eischen wrote:
> On Tue, 6 Jul 2004, Andrew Gallatin wrote:
> > Daniel Eischen writes:
> > > Note that he is holding the mutex while calling pthread_cond_signal().
> > > If we enable preemption in pthread_cond_signal(), then I suspect it
> > > would be even worse than without preemption.
> > >
> > > I think the only place where it is sane to enable preemption is
> > > on pthread_mutex_unlock().
> > That certainly makes sense to me. But I don't want to see you
> > optimize the threads lib just for my app. I can always put in an
> > #ifdef FreeBSD
> > pthread_yield()
> > #endif
> > But what I'm still wondering is where the ~3x slowdown (20usec linux
> > -> ~60usec, libthr) is coming from. Is this a factor of the context
> > switch time and ithreads?
> I suspect our kernel is butt-slow compared with Linux in general.
> Mysql under native linux is similarly faster.
It'd be interesting to see a kernel compiled with config -p
and the result of the profiling.. (when nothing else is running.)
I presume all teh debugging is turned off.
> > I need to move the driver to a fast interrupt and I need to test
> > SCHED_BSD as well. I should probably cvs update to get jhb's
> > scheduling changes.
> Dan Eischen
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