RE: rsockets and fork

Sridhar Samudrala
2012-08-18T00:34:20Z

On Fri, 2012-08-17 at 22:36 +0000, Hefty, Sean wrote:
> > > retries = 0, err = 0, index = 16, ctrl_avail = 3, sqe_avail = 1020,
> >
> > ^^^^^^^^^^^^^^
> > This looks like part of the problem. There should be 4 control messages
> > available by default. The receiver has sent a control message to the sender,
> > but the control message never completed at the receiver. My guess is that the
> > sender never received it either. It may be the missing buffer update, which
> > would be an RDMA write into the sender's 'target_sgl' array.
> >
> > Have you ever been able to reproduce this problem without using fork() support?
>
> A simple check to add is whether the rs_post_write() call ever fails, but in rs_send_credits() in particular. Checking for an error from ibv_get_cq_event() in rs_get_cq_event() may also be useful. In neither case do I expect an error, but we could confirm it.

I didn't see any errors with these calls.
So far i have been able to consistently reproduce this hang only when fork support is enabled.
I am seeing this issue randomly even with a simple tcp client/server test only with fork.

Thanks
Sridhar