Re: [PATCH v7 0/5] Make cpuid <-> nodeid mapping persistent

[Zhu Guihua]

Hi,

On 05/19/2016 10:46 PM, Peter Zijlstra wrote:
> On Thu, May 19, 2016 at 06:39:41PM +0800, Zhu Guihua wrote:
> > [Problem]
> >
> > cpuid <-> nodeid mapping is firstly established at boot time. And workqueue caches
> > the mapping in wq_numa_possible_cpumask in wq_numa_init() at boot time.
> >
> > When doing node online/offline, cpuid <-> nodeid mapping is established/destroyed,
> > which means, cpuid <-> nodeid mapping will change if node hotplug happens. But
> > workqueue does not update wq_numa_possible_cpumask.
> So why are you not fixing up wq_numa_possible_cpumask instead? That
> seems the far easier solution.

We tried to do that. You can see our patch at
http://www.gossamer-threads.com/lists/linux/kernel/2116748

But maintainer thought, we should establish persistent cpuid<->nodeid 
relationship,
there is no need to change the map.

Cc TJ,
Could we return to workqueue to fix this?

Thanks,
Zhu

> Do all the other archs that support NUMA and HOTPLUG have the mapping
> stable, or will you now go fix each and every one of them?
>
>
> .