Re: [RFC 2/2] x86_64: expand kernel stack to 16K

Dave Chinner
2014-05-28T23:17:16Z

On Wed, May 28, 2014 at 03:42:18PM -0700, H. Peter Anvin wrote:
> On 05/28/2014 03:11 PM, Dave Chinner wrote:
> > On Wed, May 28, 2014 at 07:23:23AM -0700, H. Peter Anvin wrote:
> >> We tried for 4K on x86-64, too, for b quite a while as I recall.
> >> The kernel stack is a one of the main costs for a thread. I would
> >> like to decouple struct thread_info from the kernel stack (PJ
> >> Waskewicz was working on that before he left Intel) but that
> >> doesn't buy us all that much.
> >>
> >> 8K additional per thread is a huge hit. XFS has indeed always
> >> been a canary, or troublespot, I suspect because it originally
> >> came from another kernel where this was not an optimization
> >> target.
> >
> > <sigh>
> >
> > Always blame XFS for stack usage problems.
> >
> > Even when the reported problem is from IO to an ext4 filesystem.
> >
>
> You were the one calling it a canary.

That doesn't mean it's to blame. Don't shoot the messenger...

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com