[ofa-general] Re: iWARP peer-to-peer CM proposal

[Kanevsky, Arkady]

Another small discreptancy between IB and iWARP.
Since RDMA_CM is used for ULP which are transport
independent they will follow the stricter rule.
That is IB. For IB any posting to SQ prior to QP
being in RTS state shall be flushed.

This semantic is actually very useful for ULPs which
use insignalled completions. Because, once you see
the completion for the request you posted after connection
failure you are sure that all previously posted request on the
same SQ are completed and had you had seen them all.

So while, you are correct on the spec since we are working
in IW_CM we can assume IB semantic on posting.

Thanks,

Arkady Kanevsky                       email: arkady at netapp.com
Network Appliance Inc.               phone: 781-768-5395
1601 Trapelo Rd. - Suite 16.        Fax: 781-895-1195
Waltham, MA 02451                   central phone: 781-768-5300
 

> -----Original Message-----
> From: Steve Wise [mailto:swise at opengridcomputing.com] 
> Sent: Wednesday, November 28, 2007 1:52 PM
> To: Kanevsky, Arkady
> Cc: Glenn Grundstrom; Leonid Grossman; openib-general at openib.org
> Subject: Re: [ofa-general] Re: iWARP peer-to-peer CM proposal
> 
> Kanevsky, Arkady wrote:
> > ULP can post recvs before connection is established but not to send 
> > queue prior to connection establishment.
> > 
> 
> I hate quoting specs (and the RDMAC verbs spec isn't really any 
> standard), but, page 25 of draft-hilland-iwarp-verbs-v1.0 
> indicates its 
> ok to post SQ WRs when in idle:
> 
> ----
> The QP MUST be in the Idle state following QP creation or 
> when moved to 
> this state with Modify QP. In this state, Send or Receive WRs MAY be 
> posted but they MUST NOT be processed and CQEs MUST NOT be generated.
> ----
>