Re: [PATCH] x86, sched: allow topolgies where NUMA nodes share an LLC

[Peter Zijlstra]

On Thu, Jun 08, 2017 at 12:39:28PM -0700, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> Our SMP boot code has a series of assumptions about what NUMA
> nodes are that are enforced via topology_sane().  Once upon a
> time, we verified that a CPU package only contained a single node
> (fixed in cebf15eb0).  Today, we verify that SMT siblings and
> LLCs do not span nodes.
> 
> The SMT siblings assumption is safe, but the LLC is violated on
> current hardware.

What does? That does sound broken. How can a cache domain sanely span
memory controllers?

This needs far more explanation.