Related Topics:
Related Topics:| Choosing the Data to Collect |
In multithreaded or MPI programs, synchronization wait tracing keeps track of real-time delays in calls to thread-synchronization or MPI barrier routines if the delay exceeds a certain predetermined threshold. Each data point contains time stamps for the beginning and the end of the delay, and the IDs of the thread and LWP running at the end of the delay.
The threshold can be set to a time value, or determined by a calibration test in which calls are made to the synchronization routines without any synchronization delay. The threshold is the average time for these calls multiplied by an arbitrary factor. This procedure prevents the recording of events for which the wait times are due only to the call itself and not to a real delay.
Synchronization-delay information is converted into the following metrics: