locksandwaits Command Line Analysis

Note

This analysis is deprecated in the GUI and available from the command line only. Threading analysis combines and replaces the Concurrency and Locks and Waits analysis types available in previous versions of Intel® VTune™ Amplifier. Use the Threading analysis from either the command line or GUI.

While Concurrency analysis helps identify where your application is not parallel, Locks and Waits analysis helps identify the cause of ineffective processor utilization. One of the most common problems is threads waiting too long on synchronization objects (locks). Performance suffers when waits occur while cores are under-utilized.

Locks and Waits analysis uses user-mode sampling and tracing collection. With this analysis you can estimate the impact each synchronization object has on the application and understand how long the application had to wait on each synchronization object, or in blocking APIs, such as sleep and blocking I/O.

There are two groups of synchronization objects supported by the Intel® VTune™ Amplifier:

  • objects usually used for synchronization between threads, such as Mutex or Semaphore

  • objects associated with waits on I/O operations, such as Stream

Syntax

$ amplxe-cl -collect locksandwaits [-knob <knobName=knobValue>] [--] <target>

Knobs: sampling-interval, enable-user-tasks, enable-user-sync

Note

For the most current information on available knobs (configuration options) for the Locks and Waits analysis, enter:

$ amplxe-cl -help collect locksandwaits

Example

This example shows how to run the Locks and Waits analysis on a Linux* myApplication app with the enabled User synchronization API profiling:

$ amplxe-cl -collect locksandwaits -knob enable-user-sync=true -- home/test/myApplication

What's Next

When the data collection is complete, do one of the following to view the result:

For more complete information about compiler optimizations, see our Optimization Notice.
Select sticky button color: 
Orange (only for download buttons)