Re: Context switching and Xeon processors

"Brandon Metcalf" <bmetcalf@nortel.com> writes:
> We've been tuning the kernel (2.4 SMP flavor) and have improved
> performance quite a bit.  I'm now wondering if turning off HT will
> improve performance even more.  Based on the vmstat output below, is
> the context switching typical or too high?

Given that your CPU usage is hovering around 2%, it's highly unlikely
that you'll be able to measure any change at all by fiddling with HT.
What you need to be working on is disk I/O --- the "80% wait" number
is what should be getting your attention, not the CS number.

(FWIW, on the sort of hardware you're talking about, I wouldn't worry
about CS rates lower than maybe 10000/sec --- the hardware can sustain
well over 10x that.)

            regards, tom lane