Linux : how to turn on/off CPU logically

I referred to the following URL.

CPU hotplug Support in Linux(tm) Kernel

http://www.cyberciti.biz/files/linux-kernel/Documentation/cpu-hotplug.txt

[ procedure ]

# cat /etc/redhat-release Scientific Linux release 6.0 (Carbon) # uname -r 2.6.32-131.6.1.el6.x86_64

There are two CPUs.

# top -b -n 1 | egrep -i cpu[0-9] Cpu0  :  0.1%us,  0.1%sy,  0.0%ni, 99.3%id,  0.5%wa,  0.0%hi,  0.0%si,  0.0%st Cpu1  :  0.0%us,  0.0%sy,  0.0%ni, 99.9%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st

# egrep processor /proc/cpuinfo processor       : 0 processor       : 1

# ls /sys/devices/system/cpu/ cpu0  cpu1  cpufreq  cpuidle  kernel_max  offline  online  possible  present

trun off CPU1 logically

# cat /sys/devices/system/cpu/cpu1/online 1 # echo 0 > /sys/devices/system/cpu/cpu1/online # cat /sys/devices/system/cpu/cpu1/online 0

# dmesg CPU 1 is now offline SMP alternatives: switching to UP code # egrep processor /proc/cpuinfo processor       : 0

turn on CPU1 logically

# echo 1 > /sys/devices/system/cpu/cpu1/online

# dmesg Booting Node 0 Processor 1 APIC 0x1

# head -2 /proc/interrupts           CPU0       CPU1  0:        114          1   IO-APIC-edge      timer