Re: [RFC] memory tiering: use small chunk size and more tiers

[Bharata B Rao]

On 10/28/2022 11:16 AM, Huang, Ying wrote:
> If my understanding were correct, you think the latency / bandwidth of
> these NUMA nodes will near each other, but may be different.
> 
> Even if the latency / bandwidth of these NUMA nodes isn't exactly same,
> we should deal with that in memory types instead of memory tiers.
> There's only one abstract distance for each memory type.
> 
> So, I still believe we will not have many memory tiers with my proposal.
> 
> I don't care too much about the exact number, but want to discuss some
> general design choice,
> 
> a) Avoid to group multiple memory types into one memory tier by default
>    at most times.

Do you expect the abstract distances of two different types to be
close enough in real life (like you showed in your example with
CXL - 5000 and PMEM - 5100) that they will get assigned into same tier
most times?

Are you foreseeing that abstract distance that get mapped by sources
like HMAT would run into this issue?

Regards,
Bharata.