[openib-general] ibv_poll_cq

[Dotan Barak]

Hi.

john t wrote:
> Hi,
>  
> In one of my multi-threaded application (simple send/recv application 
> written using uverbs), I am repeatedly getting an error code 12 
> (IB_WC_RETRY_EXC_ERR) from "ibv_poll_cq". Not able to figure out 
> what is going wrong. Cam some one please give a suggestion so that I 
> can investigate on those lines.
>  
> Also, is there an error handling mechanism in IB, for ex: in the above 
> case what should I do in order to correct the problem.
This completion status means that the remote side of the QP is not 
sending any response (ack/nack/ anything ...)
You can have this completion if one of the following scenarios occurs:
* a QP tries to send a message to a remote QP which is not ready (not in 
at least RTR state)
* a QP tries to send a message to a remote QP which is being closed (or 
in error state)
* the QP parameters are not the same as the remote QP parameters (for 
example: if the PSNs are not configured with good values,
the messages may be silently dropped)


I suggest to:
     sync between the 2 sides before starting to work with the QPs
    sync between the 2 sides before stop to work with the QPs
    You can increase the number of retry_cnt / timeout attributes in the 
QP context

you should make sure that the timeout value is not 0 (Zero).


Dotan