Re: What is the PREEMPTION option good for?

Robert Watson wrote:

There's a known performance regression with PREEMPTION and loopback
network traffic on UP or UP-like systems due to a poor series of context
switches occuring in the network stack. If your benchmark involves the
above web load over the loopback, that could be the source of what
you're seeing. If it's not loopback traffic, then that's not the source
of the problem.

The dynamic stuff is accessing the database (fairly intensively) over
the loopback.

You might try fiddling with kern.sched.ipiwakeup.enabled and see what
the effect is, btw -- this controls whether or not the scheduler wakes
up another idle CPU to run a thread when waking up that thread, rather
than queuing it to run which may occur on the other CPU at the next
clock tick.

Try this with or without PREEMPTION?

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