TITLE>Lanai Active Message Mapper </TITLE>

<h1>
        Using the Mapper
</h1>
The mapper is a program written in Active Messages which creates 
maps and routes of the network. During the routing process, the routes get
saved to files. After the routing is complete, a perl script post-processes
the routes into a format suitable for the LAM library.
<p>
The mapper requires two envirnoment variables to be set before running.
The first of these is MAP_LEVEL which is a measure of how much of the network
you wish to map (in terms of depth of the tree). Due to the way the program is
structured this value is restricted to be between 0 and 3. The second 
environment variable is the MAP_PRIORITY which is the priority of that machine.
This is similar to Myricom's priority scheme. Each host must have 
a unique priority. 
<p>
The mapper can run in two modes, "master" mode and "slave" mode. In
slave mode, (use the -s) flag, the mapper is passive and does not 
explore the network. A slave waits for maps from a "master" node
and then computes it's own routes. On a modest sized network, (like our
seven switch 32 node network), a master generates scout packets 
every 400 usec or so. This is fast enought that multiple masters 
generate deadlock and FRESes in the network. FRESes currently hose 
the LCP. The master/slave hack is to run only ONE node as a master,
and all the rest as slaves. Since only one node is sending scout 
packets, deadlock cannot occur.
<p>
You must save the output of the master and slaves into a separate 
files for each priority called XX.route. XX is the MAP_PRIORITY of that 
host. Run the genroutes.pl perl5 script to create routing files suitable 
for the Active Messages
library. See the comments in the script for how it works. You'll 
probably want the change the names of the output files. 
<p>