Re: [PATCH v4] Regression: sched: automated per session task groups

From: Mike Galbraith
Date: Sun Dec 05 2010 - 12:16:01 EST


On Sun, 2010-12-05 at 18:09 +0100, Mike Galbraith wrote:
> 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.

P.P.S :)

systemd will have the same regressions/progressions. It doesn't matter
one whit whether it's kernel/userland making policy. If distro-X
includes either one, or neither, they are guaranteed to be wrong :)

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