On Thu, 2006-03-23 at 12:34, Michael S. Tsirkin wrote: > Quoting r. Hal Rosenstock <[EMAIL PROTECTED]>: > > > > > > > > > >Sean, just to wrap it up, the API at the verbs layer will > > > > > > > > > >look > > > > > > > > > >like the below, and then ULPs just put the value they want in > > > > > > > > > >the CM and CM will pass it in to low level. > > So this is our question, right? > > > CM REQ and REP messages include the following field: > > --------------- > 12.7.26 END-TO-END FLOW CONTROL > Signifies whether the local CA actually implements End-to-End Flow Control > (1), or instead always advertises .invalid credits.(0). See section > 9.7.7.2 End-to-End (Message Level) Flow Control for more detail. > --------------- > > Consider and implementation that advertises valid credits for > connections, and always advertises invalid credits for other connections. > This is compliant since the IB spec says (end-to-end (message level) flow > control, Requester Behaviour): > "Even a responder which does generate end-to-end credits may choose to send > the > 'invalid' code in the AETH"
I did some spec reading to find this and found the following which I think makes the current requirement clear: p.347 line 37 states "HCA receive queues must generate end-to-end credits (except for QPs associated with a SRQ), but TCA receive queues are not required to do so. This appears to be informative text. I first found the following: p. 348 has the compliances for this for both HCAs and TCAs: C9-150.2.1: For QPs that are not associated with an SRQ, each HCA re- ceive queue shall generate end-to-end flow control credits. If a QP is associated with an SRQ, the HCA receive queue shall not generate end-to- end flow control credits. o9-95.2.1: Each TCA receive queue may generate end-to-end credits ex- cept for QPs that are associated with an SRQ. If a TCA supports SRQ, the TCA must not generate End-to-End Flow Control Credits for QPs associ- ated with an SRQ. C9-151: If a TCA's given receive queue generates End-to-End credits, then the corresponding send queue shall receive and respond to those credits. This is a requirement on each send queue of a CA. The above informative text also references the CA requirements in chapter 17 and on p. 1026 line 25 there is a row in the table for end to end flow control for RC consistent with the above. p.1028 has the compliances for this. > Is it compliant for CM implementations to set/clear the End-to-End Flow > Control > field accordingly, taking it to mean > > "whether the local CA actually implements End-to-End Flow Control > (1), or instead always advertises 'invalid credits'(0)" > *for the specific connection* So IMO the intent of what was written is clear (on a per CA basis) and this is a spec change which is OK to propose but needs a different writeup. -- Hal _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
