Performance Counters CPU/System Stats

CPU/System Stats

In addition to the % Processor Usage counters above, there are additional counters that can detect how the Processor is being worked and if the Processor Subsystem could potentially be a bottleneck.

\Processor(_total)\% Privileged Time

The Processor(_total)\% Privileged Time counter shows the percent of time that the processor is spent executing in Kernel (or Privileged) mode. Privileged mode includes services interrupts inside Interrupt Service Routines (ISRs), executing Deferred Procedure Calls (DPCs), Device Driver calls and other kernel-mode functions of the Windows® Operating System.
Most of the time a processor should be executing User mode operations, a high % privileged time might indicate a poorly written device driver or a faulty piece of hardware.

Microsoft® Description - % Privileged Time is the percentage of elapsed time that the process threads spent executing code in privileged mode. When a Windows system service in called, the service will often run in privileged mode to gain access to system-private data. Such data is protected from access by threads executing in user mode. Calls to the system can be explicit or implicit, such as page faults or interrupts. Unlike some early operating systems, Windows uses process boundaries for subsystem protection in addition to the traditional protection of user and privileged modes. Some work done by Windows on behalf of the application might appear in other subsystem processes in addition to the privileged time in the process.

\Processor(_total)\% User Time

The Processor(_total)\% User Time counter shows the percent of time that the processor(s) is spent executing in User mode.

Microsoft® Description - % User Time is the percentage of elapsed time the processor spends in the user mode. User mode is a restricted processing mode designed for applications, environment subsystems, and integral subsystems. The alternative, privileged mode, is designed for operating system components and allows direct access to hardware and all memory. The operating system switches application threads to privileged mode to access operating system services. This counter displays the average busy time as a percentage of the sample time.

\System\Processor Queue Length

The Processor Queue Length shows the number of threads that are observed as delayed in the processor Ready Queue and are waiting to be executed.
On single core machines, a sustained value over 5-10 or so may indicate that the workload on the system is more than the processor can handle. On multi-core systems, a good rule of thumb is to divide the Queue Length by the number of cores in the system and use the same indication above with that calculated value.
Note that the Processor Queue Length is an instantaneous counter, whereas the % Processor Usage counters are continuously measured counters that are averaged. There could be some disconnect between these counters because of this.

Microsoft® Description - Processor Queue Length is the number of threads in the processor queue. Unlike the disk counters, this counter counters, this counter shows ready threads only, not threads that are running. There is a single queue for processor time even on computers with multiple processors. Therefore, if a computer has multiple processors, you need to divide this value by the number of processors servicing the workload. A sustained processor queue of less than 10 threads per processor is normally acceptable, dependent of the workload.