opensm: file routing engine

["Paul Monday (Parallel Scientific)" <paul.monday-HFKXkVZtcVHQT0dZR+AlfA@public.gmane.org>]

I've been toying with the file routing engine implementation for some 
work I'm doing, but I'm finding very little documentation on it.  I only 
have one switch to experiment with at the moment as well so some of the 
information in the lid / lfts files that are generated are not obvious 
for how they expand to a multiple switch environment.  Perhaps there is 
a document around since I'm a RTFM type of person?

At any rate, here's what I've gathered with 4. being the big question.

1. The easiest way to get started with the file routing engine is to 
generate the lid / lfts using a different routing engine.  I went ahead 
and did the following:  opensm -D 0x40 -R ftree
2. Once run, copy the /var/log/opensm-lfts.dump and 
/var/log/opensm-lid-matrix.dump files elsewhere for use
3. I've tried to generalize the file contents below
4. Modify the opensm-lid-matrix.dump file to "implement" or "tweak" the 
routing algorithm over the physical network?
5. Run opensm -R file -M new-lid-matrix.dump -U new-lfts.dump

I have one other strange question ... is it possible to carve a single 
physical switch into two logical switches (put a cable between ports 
16/17 and modify the routing tables ... this seems like it wouldn't work 
as the Unicast LID / Switch: guid rows in the respective files below 
serve as keys so the single switch would be identified twice).

The file formats seem to be:

opensm-lfts.dump (later becomes -U [file])
- Contains all discovered ports (powered on), their function (Switch vs. 
Channel Adapter), their LID and some extra information.  This is 
essentially the physical network (if all machines are powered on) ... 
the format is:
Unicast lids [0-x] of switch Lid LID# guid <GUID> ('switch description'):
<LID 0xZZZZ> <SwitchPort ZZZ> # <Channel Adapter | Switch> portguid 
<GUID>: 'Descirption'

I assume this file grows with all of the Channel Adapters and switches.  
Given a switch-switch connection a row would look like
0x0019 005 # Switch portguid 0x000000000000003 'MF3:switch-my:MTS3600/U1'

You could essentially use this file to map the entire physical network, 
you would end up with a graph ... but no information for how to traverse 
it efficiently, does that sound right?

opensm-lid-matrix.dump
- Looks like it contains the hop information ... but it's a bit more 
cryptic since I have only one switch :(  It should contain a list of all 
switches, the LID for the switch and then hop information.  The hop 
information is what I'm a bit puzzled about here, as well as what port 
guid information is tacked on.  The format of the file is:
Switch: guid 0x000000000000x
<LID 0xZZZZ> 00 ff ff <hops for all ports> # portguid 0x0000000

I know ... it's a detailed question but I figured I would write enough 
so someone else wouldn't have to reverse engineer using the file routing 
engine if this is basically right.

Paul Monday
Parallel Scientific, LLC

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