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

Arjan van de Ven
2005-11-16T06:54:56Z

On Tue, 2005-11-15 at 18:56 -0500, Parag Warudkar wrote:
> On Nov 15, 2005, at 6:41 PM, Wed, 16 Nov 2005 00:41:11 +0100 wrote:
>
> >
> >> documentation for broadcom wireless:
> >> http://bcm-specs.sipsolutions.net/
> >> embrionic driver based on this spec:
> >> http://bcm43xx.berlios.de/
> >
> >
> > Maybe a good deal would be to delay the 4K patch until some
> > preliminary
> > version of those is merged?
>
> Andi had some pretty valid comments against the 4K approach.
> Here - http://lkml.org/lkml/2005/9/6/4
> I didn't see anyone contradicting his opinion. Seems very plausible
> to me.

the only argument I see is "we had overflows in 2.4 with 8k". In fact
that is part of why 4K stacks was done! With 4k/4k stacks there is MORE
stack space than in 2.4. Most of the overflows I've seen in 2.4 were
nested interrupts with complex softirqs; with the 4k/4k stack approach
interrupts have MORE stack space available than in 2.4, making overflows
less likely. In addition the 2.6 kernel has undergone a "stack diet",
the final piece of which is the IO submission change that is now in -mm.