[ofiwg] EP_RDM question

[Jeff Squyres (jsquyres)]

On Jun 30, 2016, at 1:24 PM, Hefty, Sean <sean.hefty at intel.com> wrote:
> 
>> What happens?
> 
> Provider specific  :)

Hmm.

>> 1. The lack of receive buffers at the target should trigger an error at
>> the sender indicating that message A was not delivered.
>> 
>> 2. Or:
>> 
>> 2a. If receive buffers are eventually posted at the target, message A
>> will be delivered successfully.
>> 2b. If the target endpoint is closed before receive buffers are
>> available at the target for message A, an error is triggered at the
>> sender indicating that message A was not delivered
>> 2c. If message A has not been delivered within a given timeout (for any
>> reason -- to include lack of buffers at the target), an error is
>> triggered at the sender indicating that message A was not delivered
>> 
>> In short: assuming a receiver a) continually posts receive buffers, and
>> b) doesn't close its endpoint, do senders need to worry about credits
>> with RDM endpoints?
> 
> IMO, the ideal case is option 2.  This relates to the resource management enabled attribute.  With RM disabled, option 1 is a valid way to handle the issue.  With RM enabled, I would expect the provider to implement something closer to option 2.

I don't quite grok this answer: 2a and 2b could happen together, but I kinda considered 2c to be a different option (i.e., I specifically didn't mention timeout in 2a or 2b).

I did miss the entire section on fi_domain(3) regarding resource management, though.  Reading that section, it implies that when RM is enabled -- assuming a well-behaving (set of) sender(s) and receiver -- one should not need to worry about send/receive credit schemes.

-- 
Jeff Squyres
jsquyres at cisco.com
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/