Troubleshooting guide

the other end. On the host, there will be a green LED illuminated and a flashing

yellow/amber LED illuminated on each NIC.

If the LED of a connected port is not illuminated in green, refer to "Run fm_db2wirelist

and look for any missing links". If FMS is not available, please consult the diagnostic

procedures in Appendix B "Isolating the Cause of a Hardware Problem".

If you're using an M3-CLOS-ENCL-* or M3-SPINE-ENCL-* switch, please consult the

following webpage (

http://www.myri.com/scs/14U_switches/#tft-green) for guidelines in

troubleshooting a connected port whose LED is not illuminated in green or yellow/amber.

5. Test performance between each host and NIC

We recommend the following test to verify your MX performance.

cd <install_path>/bin

./mx_dmabench

This mx_dmabench test displays the results of the hardware benchmark test of the PCI

bus with the DMA engine of the Myrinet NIC. The output of this command indicates the

maximum sustained bandwidth that can be obtained from the PCI bus, and thus provides

an upper bound on MX performance.

We recommend the following test to verify your GM performance.

cd <install_path>/bin

./gm_debug –L

This gm_debug test displays the results of the hardware benchmark test of the PCI bus

with the DMA engine of the Myrinet NIC. The output of this command indicates the

maximum sustained bandwidth that can be obtained from the PCI bus, and thus provides

an upper bound on GM performance. A detailed description of this benchmark can be

found in the FAQ entry “Can you describe in detail the “hardware benchmark of the PCI

bus” that is returned by gm_debug?” (

http://www.myri.com/cgi-bin/fom?file=121).

The output of these commands also tells you the PCI speed at which the Myrinet NIC is

running. If the PCI speed for the Myrinet NIC was not correctly detected by the BIOS,

refer to the following troubleshooting steps:

• You should first refer to the hardware documentation for the motherboard.

There could be a jumper near the PCI slots that must be set to adjust the PCI speed.

Or, there could be another PCI device that is sharing the same PCI bus as the Myrinet

NIC, and the PCI bus has been slowed to the speed of the other PCI device. Refer to

the output of /sbin/lspci –tv or /sbin/lspci –vvv to determine if there are any PCI

devices sharing the same PCI bus.