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

[Michael S. Tsirkin]

Quoting r. Sean Hefty <mshefty at ichips.intel.com>:
> Subject: Re: Re: Re: RFC: e2e credits
> 
> 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.

I can speak for SDP. It doesn't use this.
Can SRP/iSCSI maintainers please speak up?

-- 
Michael S. Tsirkin
Staff Engineer, Mellanox Technologies