What's the proper usage of provide buffers and register buffers ?

[rzbdz]

I learn that register syscall allows the kernel to take long term references to internal data structures or create long term mappings of application to reducing per-I/O overhead. And the provide buffer operation can prevent the application from consuming a lot of memory.

Doesio_uring_prep_provide_buffers operation keep some mappings of the buffers in the kernel side ?

If I am writing a echo server with provide buffer operation used, should I use io_uring_register to register those buffer so as to get better performance ?

Thank you.