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Volume Number: 26
Issue Number: 01
Column Tag: Virtualization
By Neil Ticktin, Editor-in-Chief/Publisher
There are three situations in which users commonly launch a virtual machine:
For the first test, we started at the Finder and launched the virtualization application, which then immediately launched the virtual machine. The visual feedback is fairly different between Parallels Desktop and VMware Fusion when Windows first starts up. Windows actually does its startup for quite some time after reaching the desktop. In some cases, it can take minutes for Windows to complete its boot process. Most users don't care if things continue, so long as they aren't held up.
As a result, we focused on timing to the point of actually accomplishing something. In this case, we hovered over the Task Bar icons and launched the Windows Security Center window. The test ended when the window started to render. This gave us a real world scenario of being able to actually do something as opposed to Windows just looking like it was booted.
The primary difference between the last two types of VM launch test is that the computer is fully rebooted (both the virtual machine as well as Mac OS X) in between the "Adam" tests. The successive tests are launching the virtual machines and restoring them without restarting the Mac in between.
Successive tests benefit from both Mac OS X and possibly virtual machine caching, and are significantly faster. But, you may only see these types of situations if you constantly are going in and out of your virtual machine.
VMware reports that their longer suspend time is due to a design for "better correctness and to avoid user crashes." Furthermore, VMware commented that Fusion's suspend solution "includes a 3D state as part of the resume so applications can resume where left off, resulting in a slightly longer suspend/resume time." While that may be the case, we didn't experience problems on either product when resuming from suspend, even with 3D games.
As with all of our tests, we perform these tests multiple times to handle the variability that can occur. Of these, we took the best results for each product.
End result for each of these sets of tests (geomean across Mac models) is:
Figure 4: Windows OS Launch Performance
Clearly, machines with more memory take longer to restore and that accounts for some of the differences (remember, we selected RAM configurations based on VMware Fusion's default). One thing to remember as a virtualization user is that if you are going in and out of a VM often, you may want to think about using less RAM, not more. In fact, you should just use as little as you need any way for the best experience under either virtualized environment. (We suggest 512MB to 1GB for most people.)
Most benchmarking suites measure CPU performance using file compression as at least one part of their analysis. We did the same.
As a matter of interest, we used compression instead of decompression, because with today's fast computers, decompression is actually much closer to a file copy than it is to CPU work. Compression requires the system to perform analysis to do the compression, and is therefore a better measurement of CPU.
Figure 5: Virtual Machine CPU Performance