Re: [PATCH] sched/topology: Use Identity node only if required

From: Peter Zijlstra
Date: Wed Aug 08 2018 - 05:30:26 EST

On Wed, Aug 08, 2018 at 10:43:02AM +0200, Peter Zijlstra wrote:
> On Wed, Aug 08, 2018 at 01:19:42AM -0700, Srikar Dronamraju wrote:

> > We could fix the numa topology to be NUMA_DIRECT for 2 node machines, by
> > checking if sched_domains_numa_levels == 2, but then I dont know what it
> > means for a system that has only NODE but not NUMA level.
> You have a point there; I think we should not have added the NODE thing
> to sched_domains_numa_level, let me see if we can fix that sanely.

Hurm,. looking this over I don't see anything better than changing that
NUMA_DIRECT test to <= 2.

But as the comment says, DIRECT means: all nodes are directly connected,
or not a NUMA system. A system with a single node is not a NUMA system
and would thus qualify.