Tang, Changqing wrote:
Roland or Mellanox Engineers:

        We setup completion channel for a completion queue. We want to check if 
there is any
event available, and suppose there is NO event on both completion channel and 
completion queue.

        What we can do is:

        1. call select() on completion channel with zero timeout and return 0.
        2. call ibv_poll_cq() directly and return 0.

Question:

Which way has lower overhead ?
ibv_poll_cq
  We know select() has to switch to kernel mode, does ibv_poll_cq()
switch to kernel mode and may cause a context switch ?
No - it's pure user space function

Tziporet
_______________________________________________
general mailing list
[email protected]
http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general

To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general

Reply via email to