[ofa-general] Re: [Query] ib add path record cache

[Sean Hefty]

> Yes It will, and hence reduce the initial SA traffic generated on a
> big cluster...just imagin, the cluster is quite big and every node is
> trying to build its cache initially. It will create large burst of SA
> packets.

In general I agree with the notion of enhancing the cache to allow it to 
load locally from a file.  But I'd really like to get a framework merged 
upstream first before trying to add in these sort of enhancements.

Initially loading of caches on a large fabric can be limited to a single 
GetTable PR query per node, and by enabling the caches across the fabric 
at different times, the single burst to the SA can be avoided.

> Incomplete connectivity will be till first PR is requested for that
> destination, Because if its a cache miss, any how application is going
> to initiate a ib_sa_get_path_rec() and resolved PR will be added in
> cache for future reference.

ib_sa_get_path_rec() only returns a single path.  If multiple paths 
exist, adding a single path to the cache may cause all applications to 
make use of that single path.  Updating the cache on demand isn't as 
simple as it seems.

- Sean