2.2. Reducing Performance Overhead with TAU_THROTTLE

TAU automatically throttles short running functions in an effort to reduce the amount of overhead associated with profiles of such functions. This feature may be turned off by setting the environment variable TAU_THROTTLE to 0. The default rules TAU uses to determine which functions to throttle is: numcalls > 100000 && usecs/call < 10 which means that if a function executes more than 100000 times and has an inclusive time per call of less than 10 microseconds, then profiling of that function will be disabled after that threshold is reached. To change the values of numcalls and usecs/call the user may optionally set environment variables:

% setenv TAU_THROTTLE_NUMCALLS 2000000

The changes the values to 2 million and 5 microseconds per call. Functions that are throttled are marked explicitly in there names as THROTTLED.