Re: [PATCH RESEND 0/4] memory tiering: calculate abstract distance based on ACPI HMAT

Alistair Popple
2023-07-21T04:20:56Z

Thanks for this Huang, I had been hoping to take a look at it this week
but have run out of time. I'm keen to do some testing with it as well.

Hopefully next week...

Huang Ying <ying.huang@intel.com> writes:

> We have the explicit memory tiers framework to manage systems with
> multiple types of memory, e.g., DRAM in DIMM slots and CXL memory
> devices. Where, same kind of memory devices will be grouped into
> memory types, then put into memory tiers. To describe the performance
> of a memory type, abstract distance is defined. Which is in direct
> proportion to the memory latency and inversely proportional to the
> memory bandwidth. To keep the code as simple as possible, fixed
> abstract distance is used in dax/kmem to describe slow memory such as
> Optane DCPMM.
>
> To support more memory types, in this series, we added the abstract
> distance calculation algorithm management mechanism, provided a
> algorithm implementation based on ACPI HMAT, and used the general
> abstract distance calculation interface in dax/kmem driver. So,
> dax/kmem can support HBM (high bandwidth memory) in addition to the
> original Optane DCPMM.
>
> Changelog:
>
> V1 (from RFC):
>
> - Added some comments per Aneesh's comments, Thanks!
>
> Best Regards,
> Huang, Ying