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everything I want gets picked up from the dynamo process.

Although for some reason the CPU Utilization isn't being presented and recorded.

Any ideas?

Thank you


SYSTEM - Linux x86_64, Virtual Machine, running atop ESX4.0 on an IBM HS21 Blade

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migrated from Jan 17 '10 at 12:56

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I'm assuming Linux, is that correct? – James Polley Jan 8 '10 at 6:31
Just to clarify, everything works perfectly except the CPU Utilization? I believe that's what you said but I want to make sure I understand. – Joshua Nurczyk Jan 8 '10 at 17:00
yes - my mistake. Linux it is. x86_64. It's a VM to boot. – romant Jan 9 '10 at 22:22

Whether your tools works or not CPU measurement from within a VM is utterly pointless, any data you get is flawed. This is because the OS and/or tool assumes it has full control of the (actually virtual) CPU so measurement is based on load over time and time isn't linear in VM-land due to time-slicing.

Measure from the hypervisor, it's the only way to know what's going on.

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You're absolutely right - if there is contention for the CPU. In my case this is the only virtual machine running on the host apart from the ESX console itself. Understandably there is a slight hit in the guarantee and scheduling that is incurred from ESX, but am not interested in those variations. Am after the cost per io operation. – romant Jan 17 '10 at 13:40
Host utilisation is irrelevant - VM CPU measurement is ALWAYS wrong, in all circumstances - it's actually a question on in the VCP 3 & 4 exams. – Chopper3 Jan 17 '10 at 13:55
Chopper, yes - its off the 100% ideal. This isn't the issue here, as the IO cost will still be the same, as whilst the VM is 'sleeping' in between the ESX-CPU scheduling, so is the IO within that machine. – romant Jan 18 '10 at 4:29

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