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

H. Peter Anvin
2014-05-28T22:45:07Z

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.

-hpa