Re: preempt-timing-2.6.8-rc1

Joe Korty
2004-07-13T14:36:04Z

On Tue, Jul 13, 2004 at 05:28:05AM -0700, William Lee Irwin III wrote:
> This patch uses the preemption counter increments and decrements to time
> non-preemptible critical sections.
>
> This is an instrumentation patch intended to help determine the causes of
> scheduling latency related to long non-preemptible critical sections.
>
> Changes from 2.6.7-based patch:
> (1) fix unmap_vmas() check correctly this time
> (2) add touch_preempt_timing() to cond_resched_lock()
> (3) depend on preempt until it's worked out wtf goes wrong without it

You preemption-block hold times will improve *enormously* if you move all
softirq processing down to the daemon (and possibly raise the daemon to
one of the higher SCHED_RR priorities, to compensate for softirq processing
no longer happening at interrupt level).

Joe