Subject: Re: [PATCH v4] Regression: sched: automated per session task groups
From: Mike Galbraith <efault@gmx.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Nikos Chantziaras <realnc@arcor.de>, linux-kernel@vger.kernel.org
In-Reply-To: <1291568388.7521.67.camel@marge.simson.net>
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Date: Sun, 05 Dec 2010 18:09:37 +0100
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On Sun, 2010-12-05 at 17:59 +0100, Mike Galbraith wrote:
> On Sun, 2010-12-05 at 15:12 +0000, Alan Cox wrote:
> > > > As soon as you do that from the same terminal that you're going to
> > > > launch the "make" from, you're back to total lossage.  Are you going
> > > > to explain to a student that "oh, you need to create a new
> > > > gnome-terminal tab and launch firefox from that"?
> > > 
> > > Btw, most people don't do that anymore.  They don't use terminals.  They 
> > 
> > Its a regression for those who do - and often have good reason to do.
> > This is of course why you don't put policy in the kernel and the original
> > patch was bogus anyway.
> 
> What is a very clear regression is a threaded app (say firefox) vs a
> single threaded app, particularly on UP.  The per thread scheduling
> model wins hands down there, because the scheduler very heavily favors
> the threaded application.  Take that unfairness away, and you have an
> undeniable regression.  Yes, it's not black and white, never is.

P.S.  You also have an obvious _progression_ from the perspective of the
single threaded application, which may just as well be interactive.

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