Thread Concurrency

The number of active threads corresponds to the concurrency level of an application. By comparing the concurrency level with the number of processors, Intel® VTune™ Amplifier classifies how an application utilizes the processors in the system. It defines default utilization ranges depending on the number of processor cores and displays the thread concurrency in the Summary and Bottom-up window. You can change the utilization thresholds by dragging the slider in the Summary window.

Thread concurrency may be higher than CPU usage if threads are in the runnable state and not consuming CPU time. VTune Amplifier defines the Target Concurrency level for your application by default to the number of physical cores.

Utilization Type

Default color



All threads in the application are waiting - no threads are running. There can be only one node in the Thread Concurrency histogram indicating Idle utilization.


Poor utilization. By default, poor utilization is when the number of threads is under 50% of the target concurrency.


Acceptable (OK) utilization. By default, OK utilization is when the number of threads is between 51-85% of the target concurrency.


Ideal utilization. By default, ideal utilization is when the number of threads is between 86-115% of the target concurrency.


Over-utilization. By default, over-utilization is when the number of threads is more than 115% of the target concurrency.


You may set the color scheme to colorblind from Tools (Visual Studio IDE)/File (standalone interface) > Options... > Intel VTune Amplifier version> General pane. The colors of the utilization types will be shown in greyscale.

For more complete information about compiler optimizations, see our Optimization Notice.