Re: [PATCH 1/2] workqueue: update numa affinity info at node hotplug

[Lai Jiangshan <laijs@cn.fujitsu.com>]

On 01/14/2015 09:57 PM, Tejun Heo wrote:
> Hello, Lai.
> 
> On Wed, Jan 14, 2015 at 10:47:16AM +0800, Lai Jiangshan wrote:
>>> Even if that involves slightly more code, that's the right thing to do at this point.
>>
>> Right, but in currently, the workqueue will be the only user, and I don't known
>> asking who to do it, so I may keep it in the workqueue.c.
> 
> The problem is that working around this in workqueue effectively hides
> what needs to be actively looked upon and decided.  It curently isn't
> currently defined even when such mappings can change or for which
> cpus?  Are all offline cpus up for grabs or just !present ones?  These
> are questions which can only be answered / determined from NUMA side
> and the sooner we deal with this properly the better.

So the solution_B totally keeps away from this spaghetti.

> 
>>> It'd be
>>> awesome if somebody more familiar with the numa side can chime in and
>>> explain why this mapping change can't be avoided.
>>
>> I'm also looking for someone answer it.
> 
> Exactly, whoever is requiring NUMA node remapping should explain and
> justify that and how the model to handle it can only be determined
> from that.
> 
> Thanks.
>