Q-Logic IB6054601-00 D 用户手册

2 – InfiniPath Cluster Administration

Performance and Management Tips

IB6054601-00 D

2-19

Q

For SUSE 9.3 and 10.0 run this command as root:

# /sbin/chkconfig --level 12345 powersaved off

After running either of these commands, the system will need to be rebooted for 
these changes to take effect.

Higher processor speed is good. However, adding more processors is good only if 
processor speed is balanced. Adding processors with different speeds can result 
in load imbalance.

To get the best performance from SDP, especially for bandwidth tests, edit one of 
these files:

/etc/modprobe.conf (on Fedora and RHEL)

/etc/modprobe.conf.local (on SUSE and SLES)

Add the line:

options ib_sdp sdp_debug_level=4 

sdp_zcopy_thrsh_src_default=10000000

This should be a single line in the file. This sets both the debug level and the zero 
copy threshold.

InfiniPath will attempt to run each node program with CPU affinity set to a separate 
logical processor, up to the number of available logical processors. If CPU affinity 
is already set (with 

sched_setaffinity()

, or with the 

taskset

 utility), then 

InfiniPath will not change the setting.

The 

taskset

 utility can be used with 

mpirun

 to specify the mapping of MPI 

processes to logical processors. This is useful, for example, to make best use of 
available memory bandwidth or cache locality when running on dual-core SMP 
cluster nodes.

In the following example we use the NAS Parallel Benchmark’s MG (multi-grid) 
benchmark and the 

-c

 option to 

taskset

. 

$ mpirun -np 4 -ppn 2 -m $hosts taskset -c 0,2 bin/mg.B.4 

$ mpirun -np 4 -ppn 2 -m $hosts taskset -c 1,3 bin/mg.B.4 

The first command forces the programs to run on CPUs (or cores) 0 and 2. The 
second forces the programs to run on CPUs 1 and 3. Please see the 

man

 page for 

taskset

 for more information on usage.