Re: [PATCH 04/19] sched/numa: Set preferred_node based on best_cpu

Srikar Dronamraju
2018-06-04T13:49:01Z

* Peter Zijlstra <peterz@infradead.org> [2018-06-04 15:39:53]:

> > >
> > > That seems to entirely loose the active_node thing, or are you saying
> > > best_cpu already includes that? (Changelog could use a little help there
> > > I suppose)
> >
> > I think checking for active_nodes before calling sched_setnuma was a
> > mistake.
> >
> > Before this change, we may be retaining numa_preferred_nid to be the
> > source node while we select another node with better numa affinity to
> > run on. So we are creating a situation where we force a thread to run on
> > a node which is not going to be its preferred_node. So in the course of
> > regular load balancing, this task might then be moved to set
> > preferred_node which is actually not the preferred_node.
>
> Then your Changelog had better explain all that, no?
>

I had mentioned
"Modify to set the preferred node based of best_cpu."
I will update that to describe the situation.