pthread switch (was Odd KSE panic)
eischen at vigrid.com
Tue Jul 6 13:48:39 PDT 2004
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
> 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.
> 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.
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