[mpich-discuss] Implementation of MPI blocking Send

[Darius Buntinas]

MPICH2 has several interfaces to support derivative implementations.  One interface is the ADI3 or "device" interface.  You can find the device implementations in src/mpid/ .  The base MPICH2 distribution contains two device implementations: CH3 and dcmfd.  The dcmfd device is specifically for BlueGene, so you can ignore that.  The MPID_ functions are implemented by the devices, so you can find them in src/mpid/ch3/src .

The CH3 device also provides an "channel" interface for derivative implementations.  The base MPICH2 distribution has a sock channel and a nemesis channel.  You can find these in src/mpid/ch3/channels/ .  Currently nemesis is the default channel.  Nemesis uses shared memory for intranode communication, and uses network modules for internode communication.  You can find the network modules in src/mpid/ch3/channels/nemesis/nemesis/netmod .  Information on the netmod API can be found here:
    http://wiki.mcs.anl.gov/mpich2/index.php/Nemesis_Network_Module_API

I hope this helps!

-d

On Mar 25, 2011, at 9:51 AM, vaibhav dutt wrote:

> Thanks for the reply. Actually I am trying to understand the inter-node communication procedure in MPICH.
> Are there any documents/papers on it as I was not able to find one. Does MPICH use RDMA for inter node communication?
> 
> On Thu, Mar 24, 2011 at 5:28 PM, Dave Goodell <goodell at mcs.anl.gov> wrote:
> MPICH2 is a large, complicated code base.  Numerous tools have been developed over the years for navigating large, complicated codes; try grep, cscope, or ctags.
> 
> -Dave
> 
> On Mar 24, 2011, at 5:21 PM CDT, vaibhav dutt wrote:
> 
> > Hi all,
> >
> > I was trying to find out the implementation of a simple blocking send in MPICH for my research and it is given in a
> > file send.c. In that file, a routine MPID_Send is being used to send the message. But I was not able to find the implementation of
> > MPID_Send. Is the code for MPID_Send routine given in one of C++ files?
> >
> > Thanks
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