Re: [PATCH V2 3/5] RDMA/core: transport-independent access flags

[Sagi Grimberg <sagig-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 6/30/2015 8:10 PM, Hefty, Sean wrote:
>> I suggest to start consolidating to ib_create_mr() that receives an
>> extensible ib_mr_init_attr and additional attributes can be mr_roles
>> and mr_attrs.
>
> I think this makes sense, but does it really help?
> If the end result is that the app and providers basically
> end up switching on mr_attr::type, we end up reducing the
> number of APIs, but the code complexity remains the same.
>

I think it will reduce code complexity. First, the callers
will have a single API to allocate a memory key. I'm not sure why you
say that app needs to switch on mr::type, it knows which type it wants.

As for drivers, From what I've seen, usually there is a single memory
key allocation interface to the HW and for each API and drivers call it
with a slightly different attributes and maybe do some extra driver
specific logic.

Yes, probably drivers will need to switch on mr_attr::type, but maybe
just just to determine the correct HW interface and hopefully not to
a completely different logic. I think that drivers can benefit in
reduced code duplication in total.

As a first step, we can do a naive switch on mr_attr::type in the
drivers but I'd expect driver developers to change this logic in their
driver.

Thoughts?
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