Re: [Myrinet] questions

Bill Allard wrote:
> What does return from the handler passed to gm_directed_send_with_callback 
> signify?  I would be nice if it signified that that the data sent was in 
> the receiver space but I suspect it only signifies that that the data has 
> left the sending NIC.

If it returns GM_SUCCESS, that means it has been delivered, Directed 
sends are reliable. So the sender is effectively notified that the data 
has been completely written, but the receiver is not notified of anything.
Actually, there is one case where the sender can get a GM_SUCCESS but 
the data is not written on the remote side: it's when the remote buffer 
is not DMA-able (not registerted or not allocated with gm_dma_malloc). 
In this case, there will be a cryptic message on the receiving side 
about bogus page recv... Don't ask me why it does not generate a send 
completion failure, it's GM.

> Also, gm_directed_send_with_callback (or 
> gm_send_with_callback, for that matter) returns as soon as its arguments 
> have been written to the NIC, which is almost immediatedly, right?

Yes, the send operation itself return has soon as the send token has 
been written to the NIC. However, the callback is called only when the 
data has been received if reliable sends, or after the data has left the 
sender NIC if datagrams.

Patrick

----------------------------------------------------------
|   Patrick Geoffray, Ph.D.      [email protected]
|   Myricom, Inc.                http://www.myri.com
|   Cell:  865-389-8852          685 Emory Valley Rd (B)
|   Phone: 865-425-0978          Oak Ridge, TN 37830
----------------------------------------------------------