[ofa-general] SA: Retrieving multiple paths between SGID and DGID

[Hal Rosenstock]

On Wed, 2007-12-19 at 18:32 +0530, Amar Mudrankit wrote:
> Is there any way to retrieve information about all paths between 2 IB
> hosts, when their GIDs are available ? For example when OpenSM LMC is
> set to > 0.
> 
> With the ib_sa_path_rec_get() it looks like it can give only one path
> between a given Source GID and Destination GID 

That is true as it uses SubAdmGet.

> and there is no way to 
> retrieve multiple paths with a single call to the SA module. Can
> anybody please confirm the same?
> I experimented with setting values for module parameters of ib_sa.ko
> module namely :-
> 
>         paths_per_dest = 8  (I have set OpenSM LMC=3) 
>         lookup_method = 0 (Round robin way to return paths)
> 
> in an intent to retrieve multiple paths. On a single run of my module,
> it always returned me the same path on multiple calls to
> ib_sa_path_rec_get. When my  module was unloaded and loaded again, it
> returned me different path than first run. But, in this second run on
> successive calls to ib_sa_path_rec_get, it again kept returning me the
> same path as obtained on the first run. Thus, it looks like successive
> calls to ib_sa_path_rec_get is not returning me different path on each
> call. 
> 
> If I have to retrieve all 8 paths in a single call, is there any way
> that I can accomplish the same?


Multiple paths are retrieved from the SA via SubAdmGetTable rather than
SubAdmGet which is used by local_sa and it sounds like you have Sean's
local_sa module so you should be using a different API (in
include/rdma/ib_local_sa.h) and iterating over the paths.

-- Hal

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