Re: RFC: i386: kill !4KSTACKS

[Dave Jones <davej@redhat.com>]

On Sun, Sep 04, 2005 at 10:13:10PM +0200, Bas Westerbaan wrote:
 > > > Though 4K stacks are used a lot, they probably aren't used on all
 > > > configurations yet. Other situations may arise where 8K stacks may be
 > > > preferred. It is too early to kill 8K stacks imho.
 > > 
 > > Please name situations where 8K stacks may be preferred that do not
 > > involve binary-only modules.
 > 
 > I meant that there could be situations, which have not yet been found,

And the boogeyman might really exist too.
This is just hypotetical hand-waving.

 > where it could be preferred to use 8K stacks instead of 4K. When you
 > switch from having 8K stacks as default to 4K stacks without
 > possibility for 8K stacks you'd possibly encounter these yet to be
 > found situations.

Fedora kernels have been built with 4K stacks for a long time.
(Since even before the option went upstream). The only things that
have been reported to have problems with 4KB stacks are..

- NDISwrapper / driverloader.
  (Shock, horror - no-one cares).
- XFS when used in conjunction with RAID
  Fixed now ?  (Though Neil Brown does have a pending patch for md
  to make that use less stack, which will also help).
- Reiser4
  Fixed 'soon'.

 > When on the other hand the 4K stacks are set as default, leaving the
 > option in, instead of removing it, these possible situations, when
 > found, could be resolved (temporarilly) by switching back to 8K
 > stacks.
 > 
 > After a while having 4K stacks as default would be a better time to
 > decide whether to remove the option or not instead of now.

This is what was proposed not long after the option got merged.
"After a while" has passed by quite a stretch.

		Dave