add topology option

[xrmzju]

1. add topology option: DisableNodeCaches, DisableNodeAreas, DisableNodeDistances when collect topology
2. pop err to ctx when collect topologyNodes so that the caller can know it

[jaypipes]

@xrmzju Hi! Thanks for your submission! Can you tell me a little more about why you want to disable collection of NUMA topology information?

[ffromani]

I'd also love to know about the usecase. I can guess in some scenario the collection of topology data fails? If my guess is right I'd rather fix this usecase.

[ffromani]

do we need this (kinda unprecedented) level of detail or can we just have a single option controlling everything?

[ffromani]

I'm inclined to say to keep consistent with other options are handled even though we should later perhaps refactor. But I'd be consistent meantime.

[ffromani]

this usecase makes sense, but I'd rather add a new function or enhance the Warn helper to also set err, without exposing the field (just yet)

[xrmzju]

sorry i did not get your point, could you give a example code please?

[xrmzju]

some scenario the collection of topology data fails

Yes, your guess is correct. There was a failure in collecting memory area for a certain collection of topology data, but no error was raised. As a result, my program continued to run with incorrect topology information. In my scenario, I only require the CPU NUMA topology information and I do not need to consider the NodeCaches, NodeAreas, and NodeDistances. so i made the modification above

[ffromani]

some scenario the collection of topology data fails

Yes, your guess is correct. There was a failure in collecting memory area for a certain collection of topology data, but no error was raised. As a result, my program continued to run with incorrect topology information. In my scenario, I only require the CPU NUMA topology information and I do not need to consider the NodeCaches, NodeAreas, and NodeDistances. so i made the modification above

Thanks for clarifying. Could you please share a description of the hardware on which the collection fails? E.g was it a regular NUMA x86 machine? Perhaps you were using (relatively) new technology like CXL? Or was it arm?

In general I'm reluctant to add so fine control about collection of information - adds too many knobs and makes the code less regular, so I'd like to learn more about the usecase.

[xrmzju]

some scenario the collection of topology data fails

Yes, your guess is correct. There was a failure in collecting memory area for a certain collection of topology data, but no error was raised. As a result, my program continued to run with incorrect topology information. In my scenario, I only require the CPU NUMA topology information and I do not need to consider the NodeCaches, NodeAreas, and NodeDistances. so i made the modification above

Thanks for clarifying. Could you please share a description of the hardware on which the collection fails? E.g was it a regular NUMA x86 machine? Perhaps you were using (relatively) new technology like CXL? Or was it arm?

In general I'm reluctant to add so fine control about collection of information - adds too many knobs and makes the code less regular, so I'd like to learn more about the usecase.

Here is the failure message. The operating system we are using has been specifically designed by our internal team, which means there might be some bugs or unique features. However, in my current scenario, I do not require any memory area information. Therefore, I have been attempting to find a solution to bypass or skip it. I feel free to add less fine control about collection of information, maybe some option like `CPUTopologyOnly` which will disable collecting `NodeCaches` and `NodeAreas`?

[ffromani]

@xrmzju thanks for sharing. I'll try to think about a more generic solution. I'll get back ASAP.