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Date:      Wed, 29 Sep 2004 10:55:47 -0400
From:      John Baldwin <jhb@FreeBSD.org>
To:        freebsd-arch@FreeBSD.org
Cc:        Stephan Uphoff <ups@tree.com>
Subject:   Re: sched_userret priority adjustment patch for sched_4bsd
Message-ID:  <200409291055.48387.jhb@FreeBSD.org>
In-Reply-To: <1096468734.3733.1177.camel@palm.tree.com>
References:  <1096133353.53798.17613.camel@palm.tree.com> <200409281056.00870.jhb@FreeBSD.org> <1096468734.3733.1177.camel@palm.tree.com>

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On Wednesday 29 September 2004 10:38 am, Stephan Uphoff wrote:
> On Tue, 2004-09-28 at 10:56, John Baldwin wrote:
> > If A has a priority boost from tsleep() this is intentional, however. 
> > The priroity boosts from tsleep() are _supposed_ to do this so as to
> > favor interactive tasks.  Note that if you add the code to always raise
> > td_priority while in the kernel as below you may end up defeating this
> > well-known feature of the 4BSD scheduler.
>
> OK - you and Julian convinced me that this is a feature that I should
> have known about. Without test cases or interactivity benchmarks
> discussions if this is still a desirable feature are probably useless.
> I will revisit the this once test cases materialize or I have time to
> think about a benchmark (Not likely anytime soon).

That's ok.  This discussion has been very fruitful on my end at least as 
talking this out has helped me get a much better grasp on how this stuff 
works on 4.x and should be done in 5.x to obtain at least somewhat similar 
behavior.

-- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org



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