[rds-devel] what is rdma immediate data and how is it used ?

[Richard Frank]

Our planned use of immediate data (notification message of rdma 
completion) keeps the immediate data (msg) separate from the rdma data.

Having this flag exposed to the app seems appropriate.

Olaf Kirch wrote:
> Hi Or,
>
> On Tuesday 08 January 2008 13:01, Or Gerlitz wrote:
>   
>> For the cases you mentioned here, where the immediate data send is 
>> posted to the HCA immediatly after issuing the rdma read, the fence 
>> indicator bit (IBV_SEND_FENCE) must be set in the send wqe flags, else 
>>     
>
> I noticed that in the spec as well, when trying to understand some other
> aspects of RDMA.
>
> Isn't that something the application layer should take care of by default?
> As far as I can tell the spec says "bad things can happen if you're careless;
> to be on the safe side use the Fence flag". But we lose performance that way,
> right? So we could make this a sendmsg flag, as in the patch below.
>
> Olaf
>