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

Adrian Bunk
2005-12-20T18:12:15Z

On Tue, Dec 20, 2005 at 09:56:10AM -0800, David Lang wrote:
> On Tue, 20 Dec 2005, Horst von Brand wrote:
>
> >
> >"With some drawbacks" is the point: It has been determined that the
> >drawbacks are heavy enough that the 8KiB stack option should go. Given
> >there is /no/ compelling argument /against/ 4KiB stacks, even very minor
> >drawbacks are important. So first make 4KiB the standard (popular
> >distributions work that way for /years/ now, with no measurable downsides),
>
> at least one of the 'popular distributions' that switched to 4k stacks
> years ago worked around the problems that it generated by simply lableing
> the portions that didn't work with 4k stacks as 'unsupported by this
> distro' (XFS has been explicitly stated to be in this catagory in these
> discussions)

AFAIK, XFS is the only example.
And the XFS related problems have already been fixed.

> how many other corner cases are there that these distros just choose not
> to support, but need to be supported and tested for the vanilla kernel?

My count of bug reports for problems with in-kernel code with 4k stacks
after Neil's patch went into -mm is still at 0.

If 4k stacks were as unstable as you imply, why has noone been able to
point to _one single_ problem with 4k stacks that is still present
after Neil's patch went into -mm?

> also for those who are arguing that it's only dropping from 6k to 4k, you
> are forgetting that the patches to move the interrupts to a seperate stack
> have already gone into the kernel, so today it is really 8k+4k and the
> talk is to move it to 4k+4k.
>...

That's complete bullshit.

Currently, seperate irq stacks are only used with
CONFIG_4KSTACKS=y.

> David Lang

cu
Adrian

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