Re: APM support for IPoIB

[Bang Nguyen <bang.nguyen-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

  I'm experimenting with trying to model IPoIB-CM APM after RDMA-CM APM, 
particularly the protocol for loading/re-loading of the alternate path 
and will see how it goes..

Thanks, --Bang.

On 10/2/2012 9:24 PM, Bang Nguyen wrote:
>  Here is the presentation on RDMA-CM APM
>
> https://www.openfabrics.org/ofa-documents/presentations/doc_download/516-rdmacm-amp.html 
>
>
> On 10/2/2012 8:03 PM, Hefty, Sean wrote:
>>> Just a crazy thought but IPoIB could use RDMA-CM for all of its
>>> connection management stuff..this way it can leverage the APM 
>>> support in
>>> RDMA-CM..
>>>
>>> comments?...
>> ipoib predates the rdma cm, which is why it's written to the ib_cm 
>> directly.  Communication setup with the rdma cm follows these 3 steps.
>>
>> 1. address resolution - The rdma cm indirectly ends up using ipoib 
>> for this.  With ipoib, this step isn't necessary.  I think having 
>> AF_IB support would help this by avoiding this step, plus it 
>> restricts the rdma cm to using IB devices.
>> 2. route resolution (aka path record query) - Ipoib maintains its own 
>> path record cache.  It can set the rdma cm paths manually, or there 
>> would need to be some sort of rework.
>> 3. connection setup - formats the ib cm private data and exchanges 
>> messages.  The rdma cm would need to know the ipoib private data format.
>>
>> Sooo... ipoib wouldn't use address resolution.  It maintains its own 
>> path record cache, which is a significant piece of supporting APM.  
>> Ipoib probably doesn't need to maintain its own cache, but there's no 
>> decent alternative for kernel clients currently.  And connection 
>> setup using the rdma cm is only slightly easier than using the ib 
>> cm.  (I have no idea what APM support in the rdma cm looks like.)
>>
>> - Sean
>

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html