[ofa-general] timeout question

[Dotan Barak]

Hi.
Rui Machado wrote:
> Hi all,
>
> when setting the timeout in a struct ibv_qp_attr, this value
> corresponds to the Local ACK timeout which according to the Infiniband
> spec will define the transport timer timeout defined by the formula:
> 4.096uS * 2 ^Local Ack timeout". Is this right?
> And is there a value for this timeout to be considered "good practice"?
>   
This value is depend on your fabric size, on the HCA you have (and some 
more factors)..
> Also, in a client-server setup, if this timeout is set to a "big
> value" (like 30) when the server dies, the client will take that
> amount of time to realize the failure. Is this correct?
>   
Yes, after (at least) the calculated time * number of retry_count usec, 
the sender QP will get a retry exceeded
(if there was a SR which was posted without any response from the receiver).

> Thank you for the help.
>   
Dotan