Cycles per instruction (CPI) :

As we know, all the requests are served by CPU in the form of instruction sets. A single request can translated in to 100’s of instruction sets. Cycles spent per instruction is an important parameter which helps understand where CPU is spending its clock cycles. This metrics can also be expressed in the inverse form, i.e, Instructions per Cycle (IPC).

It is important to note that CPI value signifies the efficiency of instruction processing , but not of the instructions themselves.

CPU Time :

After knowing the above parameters, it is much easier to understand CPU time for a program now.

A single program will have a set of Instructions. (Instructions / Program)
Each instruction will consume a set of CPU cycles. ( Cycles / Instruction )
Each CPU cycle is based on the CPU’s clock speed ( secs / cycle)

Hence, the CPU time that you see in your profiler is :

CPU Time for a process = (No. of instructions executed) X (Cycles per Instruction) X Clock Cycle.

So the next time when you see “Time” being mentioned in your Profiler, remember the above calculations.

Ref

https://performanceengineeringin.wordpress.com/2021/07/24/performance-understanding-cpu-time