User Manual

Table Of Contents
Rev 4.60
Mellanox Technologies
127
3. Results appear in MB/s (Mega Bytes 2^20), and reflect the actual data that was
transferred, excluding headers.
4. If these results are not as expected, the problem is most probably with one or more
of the following:
Old Firmware version.
Misconfigured Flow-control: Global pause or PFC is configured wrong on the hosts, routers and-
switches. See Section 3.7,“RDMA over Converged Ethernet (RoCE),” on page 29
CPU/power options are not set to "Maximum Performance".
Issue 3.
QoS and Flow-control
Flow control settings can greatly affect results. In order to see configured settings for all of the
QoS options, open a PowerShell prompt and use "Get-NetAdapterQos"
To achieve maximum performance all of the following must exist:
1. All of the hosts, switches and routers should use the same matching flow control
settings. If Global-pause is used, all devices must be configured for it. If PFC (Prior-
ity Flow-control) is used all devices must have matching settings for all priorities.
2. ETS settings that limit speed of some priorities will greatly affect the output results.
3. Make sure Flow-Control is enabled on the Mellanox Interfaces (enabled by default).
Go to the device manager, right click the Mellanox interface go to "Advanced" and
make sure Flow-control is enabled for both TX and RX.
4. To eliminate QoS and Flow-control as the performance degrading factor, set all
devices to run with Global Pause and rerun the tests:
Set Global pause on the switches, routers.
Run "Disable-NetAdapterQos *" on all of the hosts in a PowerShell window.