Interrupt latency problems

I'm having real problems with current with heavy disk activity.

When working in X and updating ports which causes a lot of disk activity
I get *very* poor interactive responses. Keypresses can not appear for
seconds and mouse movement is very jerky and unresponsive.

I'm wondering if something is holding locks a long time in interrupt
handlers and causing mouse/keyboard interrupts to be lost?

Since this is caused by heavy disk activity then my first guess would be
the ATA driver.

Is anyone else seeing anything like this?

-- 
Paul Richards <paul_at_freebsd-services.com>
FreeBSD Services Ltd