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

Jens Axboe
2005-11-14T11:23:04Z

On Mon, Nov 14 2005, Arjan van de Ven wrote:
> On Mon, 2005-11-14 at 12:11 +0100, Jens Axboe wrote:
> > On Mon, Nov 14 2005, Arjan van de Ven wrote:
> > > On Mon, 2005-11-14 at 11:20 +0100, Pierre Ossman wrote:
> > > > Adrian Bunk wrote:
> > > > > It seems most problems with 4k stacks are already resolved.
> > > > >
> > > > > I'd like to see this patch to always use 4k stacks in -mm now for
> > > > > finding any remaining problems before submitting this patch for 2.6.16.
> > > > >
> > > > >
> > > >
> > > > Has the block layer been remade to a serial approach?
> > >
> > > yes.
> >
> > Not in mainline it hasn't.
>
> well the patch was for -mm ;)

ok :)

> >
> > Are there any recent benchmarks of 4kb vs 8kb stacks?
>
> not sure; I do know that it very much helps java (many more threads
> possible) and the VM (far less order 1 allocs). In addition the 4Kb
> allocation can be satisfied with the per cpu list of free 4Kb pages,
> while obviously an order 1 cannot and has to go global.

I realize it has nice advantages in theory, just wondering if anyone has
done a performance analysis of 4kb vs 8kb stacks lately (or at all?).

> > Is anyone shipping 4kb stack kernels?
>
> Both Fedora and RHEL are shipping this for all 2.6 based versions (eg
> FC2 and all later, RHEL4)

Cool, that's the kind of testing coverage I was hoping for.

--
Jens Axboe