User Manual

OpenSM – Subnet ManagerRev 2.1-1.0.6
Mellanox Technologies
186
For the full list of CC Manager options with all the default values, See “Configuring Congestion
Control Manager” on page 185.
For further details on the list of CC Manager options, please refer to the IB spec.
8.9.4 Configuring Congestion Control Manager Main Settings
enable
To fine-tune CC mechanism and CC Manager behavior, and set the CC manager main settings,
perform the following:
• To enables/disables Congestion Control mechanism on the fabric nodes, set the follow-
ing parameter:
• The values are: <TRUE | FALSE>.
• The default is: True
num_hosts
• CC manager configures CC mechanism behavior based on the fabric size. The larger the
fabric is, the more aggressive CC mechanism is in its response to congestion. To manu-
ally modify CC manager behavior by providing it with an arbitrary fabric size, set the
following parameter:
• The values are: [0-48K].
• The default is: 0 (base on the CCT calculation on the current subnet size)
marking_rate
• The smaller the number value of the parameter, the faster HCAs will respond to the con-
gestion and will throttle the traffic. Note that if the number is too low, it will result in
suboptimal bandwidth. To change the mean number of packets between marking eligi-
ble packets with a FECN, set the following parameter:
• The values are: [0-0xffff].
• The default is: 0xa
packet_size
• You can set the minimal packet size that can be marked with FECN. Any packet less
than this size [bytes] will not be marked with FECN. To do so, set the following param-
eter:
• The values are: [0-0x3fc0].
• The default is: 0x200
To turn CC OFF, set 'enable' to 'FALSE' in the Congestion Control Manager configura-
tion file, and run OpenSM ones with this configuration.