[openib-general] Re: Re: RFC: e2e credits

[Sean Hefty]

Michael S. Tsirkin wrote:
>>Okay - I'm confused now.  Why have this value at all?  How does the 
>>statement above match up with C9-150.2.1: For QPs that are not associated 
>>with an SRQ, each HCA receive queue shall generate end-to-end flow control 
>>credits?
> 
> 
> Donnu.
> All this is a bit theoretical since all ULPs today always post
> receive WQEs before remote side posts sends.
> So they all can just safely disable this bit and avoid the chance
> of getting into limited state.

Right now, I'm leaning towards the idea of disabling flow control by default, 
and enabling it by request.  Are we sure that none of the ULPs (SDP, SRP, iSCSI, 
etc.) make use of this?

Making this a QP tunable parameter seems more difficult.

- Sean