17 Notes on system.cpu.util items on Windows

system.cpu.util item provides the CPU utilization percentage.

64 logical CPUs (threads) is a hard limit for 32-bit Windows systems and some old 64-bit versions, such as Windows Vista. Systems with <= 64 threads will always have one processor group (see known issues), which means it's OK to use the old performance counter "(n)% Processor Time". However, for systems with more than 64 threads Windows distributes them evenly across multiple processor groups with maximum 64 threads per single group. Given that "(n)" doesn't report values for n >= 64 we need to use "Information(g, n)" where g is a group number and n is a thread number within the group. So, for 72-thread system there will be two groups with 36 threads each and Windows will report counters "Information(0, n)" with 0 <= n <= 31 and "Information(1,n)".

When a collector process is started on Zabbix agent for Windows, the following performance counters are initialized and later used for Zabbix agent items with key system.cpu.util[n], system.cpu.util[total].

If logical CPU count is less or equal than 64 and number of CPU groups is equal to 1, then the following counters are initialized, where G is processor group count and N is processor count in group:

\Processor(_Total)\% Processor Time
       \Processor(0)\% Processor Time
       \Processor(1)\% Processor Time
       \Processor(2)\% Processor Time
       ...
       \Processor(N-1)\% Processor Time

Else:

\Processor Information(_Total)\% Processor Time
       \Processor Information(0,0)\% Processor Time
       \Processor Information(0,1)\% Processor Time
       \Processor Information(0,2)\% Processor Time
       ...
       \Processor Information(0,N-1)\% Processor Time
       ...
       \Processor Information(G-1,0)\% Processor Time
       \Processor Information(G-1,1)\% Processor Time
       \Processor Information(G-1,2)\% Processor Time
       ...
       \Processor Information(G-1,N-1)\% Processor Time