The Virtualization Cookbook for SLES 10 SP2 - z/VM - IBM

► Observe the status of the cpuplugd service:
# service cpuplugd status
cpuplugd (pid 1574) is running...
The output shows that cpuplugd starts by default in the current run level.
► Wait a few minutes and run the lscpus script again:
# lscpus
/sys/devices/system/cpu/cpu0
1
/sys/devices/system/cpu/cpu1
0
/sys/devices/system/cpu/cpu2
0
/sys/devices/system/cpu/cpu3
0
/sys/devices/system/cpu/cpu4
0
/sys/devices/system/cpu/cpu5
0
/sys/devices/system/cpu/cpu6
0
/sys/devices/system/cpu/cpu7
0
/sys/devices/system/cpu/cpu8
0
/sys/devices/system/cpu/cpu9
0
The output shows that now only one of the ten virtual CPUs are active. The cpuplugd
service turned off the other 9.
► The cpuplugd configuration file is /etc/sysconfig/cpuplugd. Some middleware products
recommend a minimum of two virtual processors. If the majority of your Linux servers will
be running a workload which recommends two processors, changed the default for
CPU_MIN to 2. An exception would be when only a single physical processor is available.
View the non-comments and lines that are not blank in the configuration file with the
following command:
# cd /etc/sysconfig
# egrep -v '^$|^#' cpuplugd
CPU_MIN="1"
CPU_MAX="0"
UPDATE="10"
CMM_MIN="0"
CMM_MAX="8192"
CMM_INC="256"
HOTPLUG="(loadavg > onumcpus + 0.75) & (idle < 10.0)"
HOTUNPLUG="(loadavg < onumcpus - 0.25) | (idle > 50)"
MEMPLUG="0"
MEMUNPLUG="0"
The default rules for the plugging and unplugging of CPUs in the configuration file is as
follow:
HOTPLUG = "(loadavg > onumcpus +0.75) & (idle < 10.0)"
HOTUNPLUG = "(loadavg < onumcpus -0.25) | (idle > 50)"
Where the variables in the statements have the following meaning:
loadavg The current average CPU load
onumcpus The number of CPUs that are online
runable_proc The current number of processes that can be run
Chapter 13. Miscellaneous recipes 211