[CentOS-virt] High CPU Usage

Shawn Everett shawn at tandac.com
Fri Dec 7 21:04:06 UTC 2012

Hi All,

I have recently installed CentOS 6.3 with QEMU+KVM for Virtualization.

 I have successfully created a Windows 2003 VM with 4GB of RAM.  The host
 server is an HP ML350 G8 with 24GB RAM and 24 cores.  Details of one of
 the cores is shown below:

 processor       : 23
 vendor_id       : GenuineIntel
 cpu family      : 6
 model           : 45
 model name      : Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
 stepping        : 7
 cpu MHz         : 1200.000
 cache size      : 15360 KB
 physical id     : 1
 siblings        : 12
 core id         : 5
 cpu cores       : 6
 apicid          : 43
 initial apicid  : 43
 fpu             : yes
 fpu_exception   : yes
 cpuid level     : 13
 wp              : yes
 flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca
 cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx
 pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good xtopology
 nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2
 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 x2apic popcnt aes xsave avx lahf_lm
 ida arat epb xsaveopt pln pts dts tpr_shadow vnmi flexpriority ept vpid
 bogomips        : 3989.86
 clflush size    : 64
 cache_alignment : 64
 address sizes   : 46 bits physical, 48 bits virtual
 power management:

 On an otherwise completely idle system I've noticed the load to be 1.0 to
 1.5 range.  Running "top" shows the culprit to be: qemu-kvm.

 Is this normal behavior?  I would have expected the load to be pretty

 Stopping the VM restores the load to normal once again.

 Is there anything I can do to reduce the load?


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