My colleague in product management, Praveen Kannan, has been working to extend Perfmon to show some ESX performance counters. This capability is automatically installed with VMware Tools on vSphere 4. But Praveen and I have made a stand-alone version available to those of you that are still on VI3. Download it here to give it a try.
To install, place the file in an appropriately-named directory on any Windows VM on VI3. Double-click the executable, which will self-extract the files into the same directory. Run "install.bat" and you're done.
Once you bring up Perfmon you'll see two new performance objects on your computer: "VM Memory" and "VM Processor". These objects contain counters exposed by ESX that accurately reflect the VM's memory and CPU usage. Here's Perfmon on my test VM after I've installed the tool.
This makes collection of host stats a breeze. Windows Management Instrumentation (WMI) programs can now easily get access to reliable host statistics. And anyone with access to Perfmon can get see their VM's resource usage. Unlike guest-based statistics, the host-statistics shown through these counters accurately reflect resource usage in the presence of virtualization overheads and time slicing of VMs.
This is a pre-release "sneak peak" version. Eventually this tool will be available for download on vmware.com and supported by VMware. But today there is no support for this tool and you're using it "as-is". Use at your own risk and do not contact VMware support for help with this release.
That's VMware's official position on this tool. But feel free to comment here with any ideas about this great new feature.