User guide

3–InfiniBand
®
Cluster Setup and Administration
Performance Settings and Management Tips
3-26 IB0054606-02 A
If cpuspeed or powersaved are being used as part of implementing Turbo
modes to increase CPU speed, then they can be left on. With these daemons left
on, IB micro-benchmark performance results may be more variable from
run-to-run.
For compute nodes, set the default runlevel to 3 to reduce overheads due to
unneeded processes. Reboot the system for this change to take effect.
Default Parameter Settings
The qib driver makes certain settings by default based on a check of which CPUs
are in the system. Since these are done by default, no user- or
ipath_perf_tuning-generated changes need to be made in the modprobe
configuration file. It doesn't hurt anything if these settings are in the file, but they
are not necessary.
On all systems, the qib driver behaves as if the following parameters were set:
rcvhdrcnt=4096
If you run a script, such as the following:
for x in /sys/module/ib_qib/parameters/*; do echo $(basename
$x) $(cat $x); done
Then in the list of qib parameters, you should see the following parameter being
discussed:
. . .
rcvhdrcnt 0
The 0 means the driver automatically sets these parameters. Therefore, neither
the user nor the ipath_perf_tuning script should modify these parameters.
Compute-only Node (Not part of a parallel file system cluster)
No tuning is required, other than what is in the Systems in General (With Either
Intel or AMD CPUs) section.
For more details on settings that are specific to either Intel or AMD CPUs, refer to
the following sections for details on systems with those types of CPUs.
Storage Node (for example, Lustre/GPFS client or server node)
Although termed a “Storage Node” this information includes nodes that are
primarily compute nodes, but also act as clients of a parallel file server.