cvs commit: src/sys/kern sched_ule.c

[Alfred Perlstein]

* Alfred Perlstein <alfred at freebsd.org> [070126 14:34] wrote:
> * Jeff Roberson <jroberson at chesapeake.net> [070125 19:47] wrote:
> > 
> > On Thu, 25 Jan 2007, Jeff Roberson wrote:
> > 
> > >jeff        2007-01-25 23:52:00 UTC
> > >
> > > FreeBSD src repository
> > >
> > > Modified files:
> > >   sys/kern             sched_ule.c
> > > Log:
> > >  - Implement much more intelligent ipi sending.  This algorithm tries to
> > >    minimize IPIs and rescheduling when scheduling like tasks while keeping
> > >    latency low for important threads.
> > Forgot:  Will IPI when:
> > 
> > >    1) An idle thread is running.
> > >    2) The current thread is worse than realtime and the new thread is
> > >       better than realtime.  Realtime to realtime doesn't preempt.
> > >    3) The new thread's priority is less than the threshold.
> 
> Out of curiosity, have you tried a polling mode where the idlethread
> will check a word each iteration an in effect pull a soft IPI?
> 
> I'm not sure this would help or hinder, but it is of interest to me.

(for everyone else)

as per discussion on IRC, it doesn't seem to be useful to do so
because a busy system will rarely actually run the idlethread.

-- 
- Alfred Perlstein, RED Incorporated Consulting.
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