Re: preempt-timing-2.6.8-rc1

[Nick Piggin]

William Lee Irwin III wrote:
> 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
>
>
> On Tue, Jul 13, 2004 at 10:36:00AM -0400, Joe Korty wrote:
>
> > 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).
>
>
> Plausible. Got a patch?

Make MAX_SOFTIRQ_RESTART 1?

I don't think you should make ksoftirq a realtime task, because that
defeats the purpose of having it to prevent livelocking userspace
doesn't it?

However, you may want to increase it from nice +19. Probably just to
nice 0 would be an idea.
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