Re: [2.6 patch] i386: always use 4k stacks

[Brian Gerst]

Horst von Brand wrote:
> linux-os \(Dick Johnson\) <linux-os@xxxxxxxxxxxx> wrote:
>
> [...]
>
>
> > Throughout the past two years of 4k stack-wars, I never heard why
> > such a small stack was needed (not wanted, needed). It seems that
> > everybody "knows" that smaller is better and most everybody thinks
> > that one page in ix86 land is "optimum". However I don't think
> > anybody ever even tried to analyze what was better from a technical
> > perspective. Instead it's been analyzed as religious dogma, i.e.,
> > keep the stack small, it will prevent idiots from doing bad things.
>
>
> OK, so here goes again...
>
> The kernel stack has to be contiguous in /physical/ memory. Keep the stack
> /one/ page, that way you can always get a new stack when needed (== each
> fork(2) or clone(2)). If the stack is 2 (or more) pages, you'll have to
> find (or create) a multi-page free area, and (fragmentation being what it
> is, and Linux routinely running for months at a time) you are in a whole
> new world of pain.

So what about arches where single-page stacks aren't viable (for example 
x86_64)?  Are we just screwed?

--
				Brian Gerst
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