Re: [PATCH v2] Fix fake numa on ppc

From: David Rientjes
Date: Wed Sep 02 2009 - 16:09:17 EST

On Thu, 3 Sep 2009, Balbir Singh wrote:

> > Right, I'm proposing an alternate mapping scheme (which we've used for
> > years) for both platforms such that a cpu is bound (and is set in
> > cpumask_of_node()) to each fake node with which it has physical affinity.
> > That is the only way for zonelist ordering in node order, task migration
> > from offlined cpus, correct sched domains, etc. ÂI can propose a patchset
> > for x86_64 to do exactly this if there aren't any objections and I hope
> > you'll help do ppc.
> Sounds interesting, I'd definitely be interested in seeing your
> proposal, but I would think of that as additional development on top
> of this patch

Absolutely. I'm not familiar with numa=fake on ppc, but if cpus are being
bound to nodes with which they don't have affinity, it definitely warrants
a fix such as this (although the initial value for fake_enabled looks
wrong and fake_numa_node_mapping[] can be __cpuinitdata). I'll cc you,
Ben, and Ankita on the x86_64 patches. Thanks.