Re: [tip:sched/core] x86/numa: Allow specifying node_distance() for numa=fake

David Rientjes
2012-05-31T20:49:26Z

On Wed, 9 May 2012, tip-bot for Peter Zijlstra wrote:

> Commit-ID: 94c0dd3278dd3eae52eabf0fb77d472d0dd3e373
> Gitweb: http://git.kernel.org/tip/94c0dd3278dd3eae52eabf0fb77d472d0dd3e373
> Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> AuthorDate: Wed, 18 Apr 2012 19:04:17 +0200
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Wed, 9 May 2012 13:28:59 +0200
>
> x86/numa: Allow specifying node_distance() for numa=fake
>
> Allows emulating more interesting NUMA configurations like a quad
> socket AMD Magny-Cour:
>
> "numa=fake=8:10,16,16,22,16,22,16,22,
> 16,10,22,16,22,16,22,16,
> 16,22,10,16,16,22,16,22,
> 22,16,16,10,22,16,22,16,
> 16,22,16,22,10,16,16,22,
> 22,16,22,16,16,10,22,16,
> 16,22,16,22,16,22,10,16,
> 22,16,22,16,22,16,16,10"
>
> Which has a non-fully-connected topology.
>

I like this support and I'm pretty sure you used it to reproduce my
problems with sched/numa locally, but I think it would be better to
seperate it out as a different parameter such as slit=fake so that we can
still use it to fake the SLIT of our NUMA machines without requiring
numa=fake which provides no guarantees to break the nodes along physical
boundaries.

So without seperating it out into slit=fake, we can't change this
information without changing the SLIT itself and that makes debugging
harder.