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

[Horst von Brand <vonbrand@inf.utfsm.cl>]

linux-os \(Dick Johnson\) <linux-os@analogic.com> 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.
-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513
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