Re: Is there a working cache for path record and lids etc for librdmacm?

[Mark Haywood <mark.haywood@oracle.com>]

On 12/7/20 5:28 AM, Christoph Lameter wrote:
> Looking at librdmacm/rdma_getaddrinfo():
>
> It seems that the call to the IBACM via ucma_ib_resolve() is only done
> after a regular getaddrinfo() was run. Is IBACM truly able to provide
> address resolution or is it just some strange after processing if the main
> resolution attempt fails?



getaddrinfo() is called only if 'node' or 'service' are set. Otherwise, 
'hints' are set and used.

ucma_set_ib_route() (called from rdma_resolve_route()) calls 
rdma_getaddrinfo() with 'hints' set.

Increasing the ibacm log level and then using cmtime(1), I see log 
messages that indicate that ibacm is resolving addresses.



>
> AFACIT ucma_resolve() should run before getaddrinfo()?
>
> Or is there some magic in getaddrinfo() that actually does another call to
> the IBACM daemon?
>
>
>
> What is also confusing is that the path record determination is part of
> getaddrinfo() as well. So both the address and route lookup end up in
> getaddrinfo(). Is IB therefore using the kernel to do the lookups?
>
>
>
>