[rds-devel] [ofa-general] [PATCH RFC] rds: add iwarp support

[Steve Wise]

Olaf Kirch wrote:
> On Tuesday 08 July 2008 12:11:40 Or Gerlitz wrote:
>   
>> Olaf Kirch wrote:
>>     
>>> Okay, there's a third way to fix this, which may even work with today's Oracle IPC code. The hack is to not submit the fastreg WR until we post a SEND that transmits the rkey to a peer. Then
>>>
>>>  -	we have a QP to post the WRs to
>>>  -	we post the fastreg and the SEND to the same QP,
>>> 	ensuring that the peer doesn't initiate the RDMA
>>> 	before we've set up the memory registration.
>>>       
>> Yes, as Steve noted, using the same QP for the fastreg and send that 
>> carries the rkey/stag is a must since the send should be fenced on the 
>> fastreg completion to make sure the remote side uses a valid key.
>>     
>
> One theoretical problem is what happens if the application wants to
> register a memory range and send the rkey to two peers at the same time?
> We would have to stall the second send explicitly as long as we
> haven't seen the completion for the first send.
>   

Or signal the fast_reg wr and only complete the application's register 
when the fastreg wr completes...