From: Con Kolivas <kernel@kolivas.org>
To: MIke Galbraith <efault@gmx.de>
Subject: Re: 2.6 vs 2.4, ssh terminal slowdown
Date: Mon, 13 Feb 2006 17:08:51 +1100
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Cc: Lee Revell <rlrevell@joe-job.com>,
       Jan Engelhardt <jengelh@linux01.gwdg.de>, gcoady@gmail.com,
       linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
References: <j4kiu1de3tnck2bs7609ckmt89pfoumlbe@4ax.com> <200602131637.43335.kernel@kolivas.org> <1139810224.7935.9.camel@homer>
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On Monday 13 February 2006 16:57, MIke Galbraith wrote:
> On Mon, 2006-02-13 at 16:37 +1100, Con Kolivas wrote:
> > On Monday 13 February 2006 16:32, MIke Galbraith wrote:
> > > On Mon, 2006-02-13 at 16:05 +1100, Con Kolivas wrote:
> > > > On Monday 13 February 2006 15:59, MIke Galbraith wrote:
> > > > > Now, let's see if we can get your problem fixed with something that
> > > > > can possibly go into 2.6.16 as a bugfix.  Can you please try the
> > > > > below?
> > > >
> > > > These sorts of changes definitely need to pass through -mm first...
> > > > and don't forget -mm looks quite different to mainline.
> > >
> > > I'll leave that up to Ingo of course, and certainly have no problem
> > > with them burning in mm.  However, I must say that I personally
> > > classify these two changes as being trivial and obviously correct
> > > enough to be included in 2.6.16.
> >
> > This part I agree with:
> > -               } else
> > -                       requeue_task(next, array);
> > +               }
> >
> > The rest changes behaviour; it's not a "bug" so needs testing, should be
> > a separate patch from this part, and modified to suit -mm.
>
> Well, both change behavior, and I heartily disagree.  

The first change was the previous behaviour for some time. Your latter change 
while it makes sense has never been in the kernel. Either way I don't 
disagree with your reasoning but most things that change behaviour should go 
through -mm. The first as I said was the behaviour in mainline for some time 
till my silly requeue change.

Cheers,
Con

> Blocking a 700ms 
> sleep while allowing a 100ms sleep to bypass the same checkpoint only to
> then be multiplied by 10 is a bug.
>
> Actually, the point at which a task becomes interactive is the point at
> which scheduler semantics change.  Ergo, as far as I'm concerned, this
> should be a boundary which must be crossed before proceeding further.
> That, I agree, would be a behavioral change which should be baked in mm.
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