Re: [PATCH v5 00/27] IB/Verbs: IB Management Helpers

[Doug Ledford]

On Tue, 2015-04-21 at 23:36 +0000, Liran Liss wrote:
> Hi Michael,
> 
> The spirit of this patch-set is great, but I think that we need to clarify some concepts.
> Since this will affect the whole patch-set, I am laying out my concerns here instead.
> 
> A suggestion for the resulting management helpers is given below.
> I believe the result would be much more coherent.
> --Liran
> 
> In general
> ========
> 
> An ib_dev (or a port of) should be distinguished by 3 qualifiers:
> - The link layer:
> -- Ethernet (shared by iWARP, USNIC, and ROCE)
> -- Infiniband
> 
> - The transport (*)
> -- IBTA transport (shared by IB and ROCE)
> -- iWARP transport
> -- USNIC transport
> 
> (*) Transport means both:
> - The L4 wire protocols (e.g., BTH+ headers of IBTA, optionally encapsulated by UDP in ROCEv2, or the iWARP stack)
> - The transport semantics (for example, there are slight semantic differences between IBTA and iWARP)
> 
> - The node type (**)
> -- CA
> -- Switch
> -- Router
> 
> (**) This has been extended to also encode the transport in the current code.
> At least for user-space visible APIs, we might chose to leave this for backward compatibility, but we can consider cleaning up the kernel code.
> 
> So, I think that our "old-transport" below is just fine.
> No need to change it (and you aren't, since it is currently implemented as a function).
> 
> The "new-transport" does not really exist, but is broken into several capability checks of the L4 transport, optionally with conditions on the link type.
> I would remove the table below and tell what we really want to achieve:
> ==> move technology-specific feature-check logic out of the (multiple!) IB code components and various ULPs into per-feature helpers.
> 
> 
> Detailed remarks
> ==============
> 
> 1) The introduction of cap_*_*() stuff should have been introduced directly in patch 02/27.
> This back-and-forth between rdma_ib_or_iboe() and cap_* is confusing and increases the number of patches in the patch-set.
> Do this and remove patches 16-24.
> 
> 2)The name rdma_tech_* is lame.
> rdma_transport_*(), adhering to the above (*) remark, is much better.
> For example, both IB and ROCE *do* use the same transport. 

I especially want to second this.  I haven't really been happy with the
rdma_tech_* names at all.


-- 
Doug Ledford <dledford@xxxxxxxxxx>
              GPG KeyID: 0E572FDD

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