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I am using normal PC with the following specifications:

  1. Intel Core 2 6600 @ 2.40GHz
  2. RAM: 2G
  3. Motherboard: Intel DG965RY
  4. HDD: 7200 rpm @ 250G

I have enabled Intel VT in BIOS setting.

I install the latest Fedora 15 and KVM enabled. I installed both Windows XP x64 and Windows 7 x64 as guest OS. The installation time is taking longer as compare to native installation on same machine. After the lengthy installation, I enable remote desktop for both windows instances. I continue configure the windows and found that lot of operations seems slow and lagging.

I then use Passmark to benchmark these virtual machines. The overall rating is only 273. I then try to benchmark native windows on the same machine and the rating is 613.

Obviously KVM does not perform at near native speed.

I then try Citrix XenServer on same machine. Installing Windows and using the Windows guest is smooth. The Passmark benchmark rating is 644. This rating is near native rating.

It seems that XEN deliver the promise promptly. Or perhaps there are ways to tune the KVM to boost it's performance.

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How much memory have you allocated to each instance? IIRC, Some VM's allocate exactly the amount you set for each VM, so with only 2GB of ram you are probably swapping a whole lot, causing performance issues. The obvious fix would be to get more than 2GB of ram, because low amounts of ram in addition to a slow CPU cause major performance issues.

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Yup, first thing I thought when I read the question was "not enough RAM". – user3463 Jun 15 '11 at 3:51
512M for Windows XP. 1024M for Windows 7. I use same RAM configuration for both KVM and XEN – Chau Chee Yang Jun 15 '11 at 6:10

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