How should I be calculating per VE CPU usage
I'm reading the values from /proc/vz/vestat
idle_c is the change in number of idle cycles
user_j, nice_j, system_j is the change in usage in jiffies
$cpu_usage = 100 - (idle_c / (user_j + nice_j + system_j + idle_c) * 100);
To me the above seems incorrect because I'm mixing cycles and jiffies.
I've found the following definitions of jiffies and cycles
$seconds = $jiffies / $CONFIG_HZ;
$seconds = $cycles / $CPU_FREQ;
So I should be able rework this to:
$jiffies = $cycles / $CPU_FREQ * $CONFIG_HZ;
My code becomes:
$idle_j = $idle_c / $CPU_FREQ * $CONFIG_HZ;
$cpu_usage = 100 - (idle_j / (user_j + nice_j + system_j + idle_j) * 100);
Am I completely off base?
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