Troubleshooting guide

significantly degraded performance. For a list of all options to gm_allsize, type
gm_allsize –help or refer to the FAQ. For sample output of gm_allsize,
refer to the FAQ entry “What are the run-time options to gm_allsize?”
(http://www.myri.com/cgi-bin/fom?file=79).
Latency
To test the GM latency between two hosts (host1 and host2), type the following
on host1:
gm_allsize –slave
and on host2 type:
gm_allsize --remote-host=host1 --geometric
The output from this command will consist of two columns of data: the first
column lists the message size (in bytes), and the second column lists the latency
(in microseconds).
Unidirectional Bandwidth
To test the unidirectional bandwidth between two hosts (host1 and host2), type
the following on host1:
gm_allsize --slave --size=15
and on host2 type:
gm_allsize --unidirectional --bandwidth \
--remote-host=host1 --size=15 --geometric
where the length of the messages sent is 2**(size - 8) bytes. Unidirectional
bandwidth is a PingPing test, measuring the startup and throughput of a single
message sent between two processes, where messages are obstructed by
oncoming messages.
The output from this command will consist of two columns of data: the first
column lists the message size (in bytes) and the second column lists the
bandwidth (in MB/s).
Bidirectional (Summed) Bandwidth
To test the bidirectional (summed) bandwidth between two hosts (host1 and
host2), type the following on host1:
gm_allsize --slave --size=15
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