Re: [PATCH v3] x86, sched: Treat Intel SNC topology as default, COD as exception

[Peter Zijlstra]

On Wed, Mar 10, 2021 at 11:02:33AM -0800, Alison Schofield wrote:
> Commit 1340ccfa9a9a ("x86,sched: Allow topologies where NUMA nodes
> share an LLC") added a vendor and model specific check to never
> call topology_sane() for Intel Skylake Server systems where NUMA
> nodes share an LLC.
> 
> Intel Ice Lake and Sapphire Rapids CPUs also enumerate an LLC that is
> shared by multiple NUMA nodes. The LLC on these CPUs is shared for
> off-package data access but private to the NUMA node for on-package
> access. Rather than managing a list of allowable SNC topologies, make
> this SNC topology the default, and treat Intel's Cluster-On-Die (COD)
> topology as the exception.
> 
> In SNC mode, Sky Lake, Ice Lake, and Sapphire Rapids servers do not
> emit this warning:
> 
> sched: CPU #3's llc-sibling CPU #0 is not on the same node! [node: 1 != 0]. Ignoring dependency.
> 
> Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Suggested-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx>

Seeing how this is basically what I gave you earlier; but now tested and
with comments on,

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Boris, will you make it happen, or you want me to queue it somewhere
x86/core like?