linux-kernel - Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

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Date:	Sat, 14 Jul 2007 14:42:04 -0500
From:	Matt Mackall <mpm@...enic.com>
To:	Jesper Juhl <jesper.juhl@...il.com>
Cc:	Jeremy Fitzhardinge <jeremy@...p.org>,
	Ray Lee <ray-lk@...rabbit.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	William Lee Irwin III <wli@...omorphy.com>
Subject: Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

On Fri, Jul 13, 2007 at 04:25:56AM +0200, Jesper Juhl wrote:
> On 13/07/07, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
> >Jesper Juhl wrote:
> >> If, on the other hand, we consider 4K stacks to be the superior
> >> solution, then we should work to get all code fixed to be able to
> >> handle it so that it's actually something distros will start to enable
> >> so that we can eventually get rid of the 8K stack option alltogether.
> >> Making 4K stacks default and no longer a debug option is just the
> >> first step in that direction.
> >
> >First step is to apply wli's patch which makes separate interrupt stacks
> >orthogonal to the 4K stack option.
> >
> Yes and no.  If that will get things moving in the direction of
> getting rid of the stack size as a config option, then I'm all for it.
> But on the other hand it is my personal opinion that this is an area
> where we should just make up our minds as to whether we want 4K or 8K
> stacks and whether we want interrupt stacks or not, and then not have
> it configurable at all.  I believe the goal is 4K stacks + interrupt
> stacks, so let's just aim for that and get rid of the configurability
> of the damn thing - make a choice, make it work, make it be that
> that's what we use and rid ourselves of the alternatives...

There are two downsides to interrupt stacks:

- an extra 4k/8k used per CPU
- stack switch time

Both of those are pretty minimal. And I'd be surprised if the latter
was measurable. 

-- 
Mathematics is the supreme nostalgia of our time.
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