User guide

3–InfiniBand
®
Cluster Setup and Administration
Performance Settings and Management Tips
IB0054606-02 A 3-31
Additional Driver Module Parameter Tunings Available
Setting driver module parameters on Per-unit or Per-port basis
The ib_qib driver allows the setting of different driver parameter values for the
individual HCAs and ports. This allows the user to specify different values for each
port on a HCA or different values for each HCA in the system. This feature is used
when there is a need to tune one HCA or port for a particular type of traffic, and a
different HCA or port for another type of traffic, for example, compute versus
storage traffic.
Not all driver parameters support per-unit or per-port values. The driver
parameters which can be used with the new syntax are listed below:
Per-unit parameters:
 singleport – Use only IB port 1; more per-port buffer space
 cfgctxts – Set max number of contexts to use
 pcie_caps – Max PCIe tuning: MaxPayload, MaxReadReq
Per-port parameters:
 ibmtu – Set max IB MTU
 krcvqs – number of kernel receive queues
 num_vls – Set number of Virtual Lanes to use
Specifying individual unit/port values is done by using a specific module
parameter syntax:
param name=[default,][unit[:port]=value]
Where:
 param name is the driver module parameter name (listed above)
 default is the default value for that parameter. This value will be
used for all remaining units/port which have not had individual values
set. If no individual unit/port values have been specified, the default
value will be used for all units/ports
 unit is the index of the HCA unit (as seen by the driver). This value is
0-based (index of first unit is '0').
 port is the port number on that HCA. This value is 1-based (number
of first port is '1').