spin_count and cpu usage

Hi

I was wondering if anyone know how is spin_count measured? In CPU CYCLES?

I havea doubt with CPU usage as well, I undersstand that in v$sysstat it is using centiseconds to measure CPU usage. I wonder how can we determine 1 centisecond is equivalent to how many CPU cycles? For example I have a server with 8 PA-RISC 1200 MHz CPU, in 1 hour it reports 3 million centiseconds usage, am I using fully? Basically is how do you know how efficiently is your CPU working from Oracle Statistics.

TIA Alex

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