[CentOS-virt] High CPU Usage
Dennis Jacobfeuerborn
dennisml at conversis.de
Fri Dec 7 22:19:55 UTC 2012
On 12/07/2012 10:04 PM, Shawn Everett wrote:
> 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
> light.
>
> Stopping the VM restores the load to normal once again.
>
> Is there anything I can do to reduce the load?
You probably have 12 cores and thanks to hyper-threading that gives you 24
threads (big difference).
Have you installed the virtio drivers in the VM? That might reduce the load
a bit. Also was does running "vmstat 3" for about 20 seconds show?
Regards,
Dennis
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