Re: Slow speeds and PortXmitWait - Any tips?

Hi Adam,

First I would like to explain what this "PortXmitWait" counters mean.

This is not an error counter, It is a very high-resolution counter that is incremented every internal clock tick of the device whenever there is a packet queued on an
output port, and this packet cannot be sent.

This can happen whenever there is some temporary congestion in the fabric. For instance, if two nodes are sending to one node you can see this counter increment, or if there

Is a node mismatch in the rates you can see this counter increment.

When the counter increments it does not mean that any packets dropped, Packets are just stored in the buffer of the port until they can be sent.

Regarding the performance improvement, I suggest to get the latest WinOf driver for your HCA,
including upgrading the Connectx-2 firmware level to the latest (2.9.1000).

This can be found on the following link:

http://www.mellanox.com/page/products_dyn?product_family=32&mtag=windows_sw_drivers

You should also follow the tuning recommendations for performance on windows on the following tuning guide:

http://www.mellanox.com/related-docs/prod_software/Performance_Tuning_Guide_for_Mellanox_Network_Adapters.pdf

Thanks,

Karen.