Difference between revisions of "How to disable one CPU"

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1 How to see the number of active CPU[edit]

root@st:~# cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2387.14
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

processor       : 1
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2393.70
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

Hardware        : STi SoC with Flattened Device Tree
Revision        : 0000
Serial          : 0000000000000000

2 How to disable a CPU[edit]

On this example we disable CPU1

root@st:~# echo 0 > /sys/devices/system/cpu/cpu1/online
CPU1: shutdown
root@st:~# cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2387.14
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

Hardware        : STi SoC with Flattened Device Tree
Revision        : 0000
Serial          : 0000000000000000

3 How to enable a disabled CPU[edit]

On this example we enable CPU1

root@st:~# echo 1 > /sys/devices/system/cpu/cpu1/online
CPU1: shutdown
==How to see the number of active CPU==<pre>

root@st:~# cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2387.14
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

processor       : 1
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2393.70
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

Hardware        : STi SoC with Flattened Device Tree
Revision        : 0000
Serial          : 0000000000000000</pre>


==How to disable a CPU==
On this example we disable CPU1<pre>

root@st:~# echo 0 > /sys/devices/system/cpu/cpu1/online
CPU1: shutdown
root@st:~# cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 0 (v7l)
BogoMIPS        : 2387.14
Features        : swp half thumb fastmult vfp edsp neon vfpv3 tls 
CPU implementer : 0x41
CPU architecture: 7
CPU variant     : 0x3
CPU part        : 0xc09
CPU revision    : 0

Hardware        : STi SoC with Flattened Device Tree
Revision        : 0000
Serial          : 0000000000000000</pre>


==How to enable a disabled CPU==
On this example we enable CPU1<pre>

root@st:~# echo 1 > /sys/devices/system/cpu/cpu1/online
CPU1: shutdown</pre>


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CPU1: shutdown
 
CPU1: shutdown
 
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