[RFC PATCH v1 0/5] Adjust wording for NUMA vs. socket ID in DPDK

[Burakov, Anatoly]

On 9/6/2024 2:37 PM, Morten Brørup wrote:
>> From: Anatoly Burakov [mailto:anatoly.burakov at intel.com]
>> Sent: Friday, 6 September 2024 13.47
>> To: dev at dpdk.org
>> Subject: [RFC PATCH v1 0/5] Adjust wording for NUMA vs. socket ID in DPDK
>>
>> While initially, DPDK has used the term "socket ID" to refer to physical
>> package
>> ID, the last time DPDK read "physical_package_id" for socket ID was ~9 years
>> ago, so it's been a while since we've actually switched over to using the term
>> "socket" to mean "NUMA node".
>>
>> This wasn't a problem before, as most systems had one NUMA node per physical
>> socket. However, in the last few years, more and more systems have multiple
>> NUMA
>> nodes per physical CPU socket. Since DPDK used NUMA nodes already, the
>> transition was pretty seamless, however now we're faced with a situation when
>> most of our documentation still uses outdated terms, and our API is ripe with
>> references to "sockets" when in actuality we mean "NUMA nodes". This could be
>> a
>> source of confusion.
>>
>> While completely renaming all of our API's would be a huge effort, will take a
>> long time and arguably wouldn't even be worth the API breakages (given that
>> this
>> mismatch between terminology and reality is implicitly understood by most
>> people
>> working on DPDK, and so this isn't so much of a problem in practice), we can
>> do
>> some tweaks around the edges and at least document this unfortunate reality.
>>
>> This patchset suggests the following changes:
>>
>> - Update rte_socket/rte_lcore documentation to refer to NUMA nodes rather than
>> sockets - Rename internal structures' fields to better reflect this intention
>> -
>> Rename --socket-mem/--socket-limit flags to refer to NUMA rather than sockets
>> -
>> Add internal API to get physical package ID [1]
>>
>> The documentation is updated to refer to new EAL flags, but is otherwise left
>> untouched, and instead the entry in "glossary" is amended to indicate that
>> when
>> DPDK documentation refers to "sockets", it actually means "NUMA ID's". As next
>> steps, we could rename all API parameters to refer to NUMA ID rather than
>> socket
>> ID - this would not break neither API nor ABI, and instead would be a
>> documentation change in practice.
>>
>> [1] This could be used to group lcores by physical package, see e.g.
>> discussion
>>      under this patch:
>> https://patches.dpdk.org/project/dpdk/cover/20240827151014.201-1-
>> vipin.varghese at amd.com/
> 
> Thank you for cleaning this up, Anatoly.
> 
> I would prefer to take one more step and also rename functions and parameters, e.g. rte_socket_id() -> rte_numa_id().
> 
> For backwards compatibility, macros/functions with the old names can be added.
> 

I don't think we can do such changes without deprecation notices, but 
it's a good candidate for next release.

I have thought about including parameter renames in this patchset, but 
for now I decided against doing so. I can certainly include this in the 
next revision if that's something community is willing to accept.

-- 
Thanks,
Anatoly