CPU MHz and CPU percentage performance counters

[emaredskin]

I was reading some performace graphics on a VC 2.5 (CPU usage related to ESX 3.5). The available options were CPU-MHz and CPU percentage. I expected the trend of both lines was similar (on different scale but similar). I observed that the trend is different (in correspondence of some low values of the CPU% there are high values of CPU MHz and viceversa). Could someone clarify what's the reason of the different trend ? Thanks.

[AntonVZhbankov]

Could you please provide some screenshot(s)?

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VMware vExpert '2009

http://blog.vadmin.ru

[emaredskin]

In the middle of the appended chart, the value of red indicator (CPU MHz) is quite high but the value of the grey indicator (CPU%) is quite low

[AntonVZhbankov]

Sometimes strange figures can be seen on these charts. If it does not affect any real statistics, and happens rarely - do not pay attention.

I had funny chart when switched to daylight saving time. Chart just made a loop

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VMware vExpert '2009

http://blog.vadmin.ru

[emaredskin]

I agree with you, strange figures. So should I assume this kind of trend are due to a wrong behaviour of the code ? Are there no other technical reasons why it happens ?

[AntonVZhbankov]

Time synchronization issues are the most probable reason.

I also had a very strange problem, when chart for one my VM with very steady and predictable load one day became completely different, with peaks. It looked like VM was drunk.

I spent a week trying to figure out what happened. After all I just cloned VM, created indentical bit-to-bit copy and started clone instead of original VM. Chart was steady and smooth, and is still steady and smooth.

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VMware vExpert '2009

http://blog.vadmin.ru

[emaredskin]

Anton, thanks for your suggestion