[SPDK] Inquiry about spdk_nvme_ns_cmd_dataset_management interface

[SPDK] Inquiry about spdk_nvme_ns_cmd_dataset_management interface

[Weifeng Su]

Dear SPDK community members,

I am a developer who has been using SPDK and I have been greatly 
interested in its functionality and performance. Recently, while 
studying the `spdk_nvme_ns_cmd_dataset_management` interface, I came 
across a question I would like to discuss with you and seek your insights.

 From my understanding, the `spdk_nvme_ns_cmd_dataset_management` 
interface is used for dataset management commands. I noticed that when 
executing this interface, it requires a repeated memory copy of the data 
to a buffer before performing the operation. However, deallocation 
(dealloc) is a frequent operation. I am curious to know why a zero-copy 
approach was not chosen in the implementation and whether it is possible 
to optimize it by utilizing large page memory.

I believe that a zero-copy mechanism could potentially reduce the 
overhead of memory copies, especially for operations that involve 
frequent deallocation. By constraining the usage of large page memory, 
it could further enhance the efficiency of the interface.

I would appreciate it if you could provide some insights into the design 
considerations behind the current memory copy-based approach and any 
potential plans for optimizing this particular interface. Additionally, 
if there are any best practices or guidelines for utilizing large page 
memory with SPDK, please kindly share them.

Thank you for your time and attention. I look forward to hearing from 
you and learning more about the thoughts and future improvements 
regarding spdk_nvme_ns_cmd_dataset_management.

Sincerely,
Weifeng Su