QLogic OFED+ Host Software User Guide, Rev. B

4–Running QLogic MPI on QLogic Adapters
QLogic MPI Details
TrueScale Hardware Contexts on the DDR and QDR
InfiniBand Adapters
On the QLE7240 and QLE7280 DDR adapters, adapter receive resources are
statically partitioned across the TrueScale contexts according to the number of
TrueScale contexts enabled. The following defaults are automatically set
according to the number of online CPUs in the node:
For four or less CPUs: 5 (4 + 1 for kernel)
For five to eight CPUs: 9 (8 + 1 for kernel)
For nine or more CPUs: 17 (16 + 1 for kernel)
On the QLE7340 and QLE7342 QDR adapters, adapter receive resources are
statically partitioned across the TrueScale contexts according to the number of
TrueScale contexts enabled. The following defaults are automatically set
according to the number of online CPUs in the node:
For four or less CPUs: 6 (4 + 2)
For five to eight CPUs: 10 (8 + 2)
For nine or more CPUs: 18 (16 + 2)
The one additional context on QDR adapters are to support the kernel on each
port.
Performance can be improved in some cases by disabling TrueScale hardware
contexts when they are not required so that the resources can be partitioned more
effectively.
To disable this behavior, explicitly configure for the number you want to use with
the cfgctxts module parameter in the file /etc/modprobe.conf (or
/etc/modprobe.conf.local on SLES).
The maximum that can be set is 17 on DDR InfiniBand Adapters and 18 on QDR
InfiniBand Adapters.
The driver must be restarted if this default is changed. See “Managing the
TrueScale Driver” on page 3-22.
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