Heavy I/O blocks FreeBSD box for several seconds

[Alexander Best]

On Wed Jul  6 11, Andriy Gapon wrote:
> on 06/07/2011 16:33 Alexander Best said the following:
> > you might also want to try enabling options IPI_PREEMPTION. no idea, if this
> > improves your situation, though.
> 
> Just in case, this option has effect for 4BSD scheduler only.

thanks. i did not know that. maybe we could add a small note to NOTES or even
mention in sched_ule(4) and sched_4bsd(4), which kernel options affect the
according scheduler.

sched_ule(4) e.g. doesn't mention kern.sched.preemption, so one can assume that
defining PREEMPTION in the kernel or not doesn't make a difference. however it
*does* make a huge difference.

i believe sched_ule(4) in general needs a lot more details about the various
sysctl vars available and their semantics.

cheers.
alex

> 
> -- 
> Andriy Gapon