Re: [RFC 2/2] mm/slub: prefer NUMA locality over slight memory saving on NUMA machines

[Vlastimil Babka]

On 8/7/23 10:39, Hyeonggon Yoo wrote:
> On Thu, Aug 3, 2023 at 11:54 PM Vlastimil Babka <vbabka@xxxxxxx> wrote:
>>
> 
> Thank you for looking at it!
> 
> Yeah, it was a PoC for what I thought "oh, it might be useful"
> and definitely I will try to measure it.
> 
>> We could also postpone this until we have tried the percpu arrays
>> improvements discussed at LSF/MM.
> 
> Possibly, but can you please share your plans/opinions on it?

Here's the very first attempt :)
https://lore.kernel.org/linux-mm/20230808095342.12637-7-vbabka@xxxxxxx/

> I think one possible way is simply to allow the cpu freelist to be
> mixed by objects from different slabs

I didn't try that way, might be much trickier than it looks.

> if we want to minimize changes, Or introduce a per cpu array similar
> to what SLAB does now.

Yes.

> And one thing I'm having difficulty understanding is - what is the
> mind behind/or impact of managing objects
> on a slab basis, other than avoiding array queues in 2007?

"The mind" is Christoph's so I'll leave that question to him :)