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Date: Mon, 23 Jul 2007 22:18:04 -0700
From: "Ray Lee" <ray-lk@madrabbit.org>
To: "Jeremy Fitzhardinge" <jeremy@goop.org>
Subject: Re: -mm merge plans for 2.6.23
Cc: "Nick Piggin" <nickpiggin@yahoo.com.au>,
       "Jesper Juhl" <jesper.juhl@gmail.com>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "ck list" <ck@vds.kolivas.org>, "Ingo Molnar" <mingo@elte.hu>,
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       linux-kernel@vger.kernel.org
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On 7/23/07, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Ray Lee wrote:
> > That said, I'm willing to run my day to day life through both a swap
> > prefetch kernel and a normal one. *However*, before I go through all
> > the work of instrumenting the damn thing, I'd really like Andrew (or
> > Linus) to lay out his acceptance criteria on the feature. Exactly what
> > *should* I be paying attention to? I've suggested keeping track of
> > process swapin delay total time, and comparing with and without. Is
> > that reasonable? Is it incomplete?
>
> Um, isn't it up to you?

Huh? I'm not Linus or Andrew, with the power to merge a patch to the
2.6 kernel, so I think that the answer to that is a really clear 'No.'

> 4. Does it make anything worse?  A lot or a little?  Rare corner
> cases, or a real world usage?  Again, numbers make the case most
> strongly.
>
> I can't say I've been following this particular feature very closely,
> but these are the fundamental questions that need to be dealt with in
> merging any significant change.  And as Nick says, historically point 4
> is very important in VM tuning changes, because "obvious" improvements
> have often ended up giving pathologically bad results on unexpected
> workloads.

Dude. My whole question was *what* numbers. Please go back and read it
all again. Maybe I was unclear, but I really don't think so.