On Tue, 2015-05-26 at 10:59 -0600, Jason Gunthorpe wrote:
> On Tue, May 26, 2015 at 09:34:40AM -0400, Doug Ledford wrote:
>
> > This is a core feature more than anything else. Namespaces for RDMA
> > devices is not unique to IB or RoCE in any way. Yet no thought has been
> > given to how this will work universally across all of the RDMA
> > capable
>
> I think if Haggi is able to follow the perscription I gave then things
> will be general.
>
> - All rdma cm ids are associated with a netdev
> - The output flow uses that netdev to restrict, configure and
> determine the output RDMA device QP
> - The input flow locates the netdev as step one and then uses the
> (netdev,ip,port) tuple to find the rdma listener, which is in turn
> tied to a netdev and is restricted/configured by it.
>
> The technology specific part is the two maps: from (input
> device,packet) to netdev, from netdev to (output device,packet)
>
> After the above clean up is done, namespace enabling is basically
> providing those two mapping functions for each technology in a way
> that can locate delegatable netdevs.
>
> The trivial case for all the ethernet techs is to provide the above
> maps that can take the (input device,VLAN) and locate the correct
> child VLAN specific netdev. The existing code to support VLAN should
> pretty much immediately enable basic namespace support for all the
> ethernet families.
>
> The big open question for ethernet is how to work without relying on
> VLAN to create delgated netdevs - typically one would use a bridge and
> veth's, which do not seem very RDMA compatible. But that doesn't need
> to be answered right now.
>
> Remember, this isn't RDMA namespaces, this is netdev namespace support
> for RDMA-CM -> very different things.
That was the point of my email. This is a very myopic view of the
feature. It *should* at least have an idea of these other things too.
> Basically, I'm happy with the generality story, if the clean up work I
> outlined turns out..
>
> > issue for usNIC as if you want namespace support there, you just start
> > the user space app in a given namespace and you are probably 90% of
> > the
>
> usNIC has no kernel facing functionality, and no interaction with
> RDMA-CM, so it is irrelevant to any discussion about RDMA-CM :(
Whether usNIC has a kernel facing functionality or not is irrelevant.
This feature isn't kernel only, it effects user space applications
launched in a namespace too. And, again, my point was that this
discussion is about RDMA-CM and it should be broader (even if the
implementation isn't broader). Due to the implementation of usNIC I
suspect it would "just work", but it would be better to know so.
--
Doug Ledford <dledford@xxxxxxxxxx>
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