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Date: Fri, 26 Jan 2007 14:34:37 -0800
From: Alfred Perlstein <alfred@freebsd.org>
To: Jeff Roberson <jroberson@chesapeake.net>
Message-ID: <20070126223437.GW56065@elvis.mu.org>
References: <200701252352.l0PNq0I4074466@repoman.freebsd.org>
	<20070125183242.T564@10.0.0.1>
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Cc: cvs-src@FreeBSD.org, Jeff Roberson <jeff@FreeBSD.org>,
	src-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/kern sched_ule.c
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* Jeff Roberson <jroberson@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.

-- 
- Alfred Perlstein, RED Incorporated Consulting.
- coder / sysadmin / FreeBSD Hacker / All that jazz -