On Sat, Apr 25, 2009 at 10:05 AM, Timothy Hayes
<hayesti@tcd.ie> wrote:
I'm not sure if it's any good or even if it's 100% accurate; but if someone gets any use out of it, that would be good.
Tim
2009/4/17 Jeff Squyres
<jsquyres@cisco.com>
On Apr 16, 2009, at 11:38 AM, Timothy Hayes wrote:
From what I understand MPI_Send will hit 3 separate layers of code before reaching the socket file descriptors you've found. The PML (Point to Point Messaging Layer) is a layer that bridges the MPI semantics from the underlying point to point communications. The standard PML implementation is called 'ob1' which is what indirectly calls the code you found. MPI_Send should go through pml_isend() or pml_send() which will request a BTL (Byte Transfer Layer) modules from the BML (BTL Management Layer) and invoke the BTL's btl_prepare_src() or btl_alloc() functions before calling the btl_send(). It becomes clearer when you step through it all with a debugger though ;-)
If you're interested, I've recently implemented a BTL component of my own and am now writing up a report on the process. It will be ready next week, so if you think it might be useful, just let me know.
--
Jeff Squyres
Cisco Systems
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