There are a number of environment variables that control APEX behavior at runtime. The variables can be defined in the environment before application execution, or specified in a file called apex.conf in the current execution directory.

Environment Variable Default Value Valid Values Description
APEX_DISABLE 0 0,1 Disable APEX during the application execution
APEX_SUSPEND 0 0,1 Suspend APEX timers and counters during the application execution
APEX_SCREEN_OUTPUT 1 0,1 Output APEX options at entry, and performance summary at exit
APEX_PROFILE_OUTPUT 0 0,1 Output TAU profile of performance summary
APEX_CSV_OUTPUT 0 0,1 Output CSV profile of performance summary
APEX_TASKGRAPH_OUTPUT 0 0,1 Output graphviz reduced taskgraph
APEX_POLICY 1 0,1 Enable APEX policy listener and execute registered policies
APEX_PROC_STAT 1 0,1 Periodically read data from /proc/stat
APEX_PROC_CPUINFO 0 0,1 Read data (once) from /proc/cpuinfo
APEX_PROC_MEMINFO 0 0,1 Periodically read data from /proc/meminfo
APEX_PROC_NET_DEV 0 0,1 Periodically read data from /proc/net/dev
APEX_PROC_SELF_STATUS 0 0,1 Periodically read data from /proc/self/status
APEX_MEASURE_CONCURRENCY 0 0,1 Periodically sample thread activity and output report at exit
APEX_MEASURE_CONCURRENCY_PERIOD 1000000 Integer Thread concurrency sampling period, in microseconds
APEX_TAU 0 0,1 Enable TAU profiling (if APEX is configured with TAU).
APEX_THROTTLE_CONCURRENCY 0 0,1 Enable thread concurrency throttling
APEX_THROTTLING_MIN_THREADS 1 0,1 Minimum threads allowed
APEX_THROTTLING_MAX_THREADS 8 0,1 Maximum threads allowed
APEX_THROTTLE_ENERGY 0 0,1 Enable energy throttling
APEX_THROTTLING_MIN_WATTS 150 Integer Minimum Watt threshold
APEX_THROTTLING_MAX_WATTS 300 Integer Maximum Watt threshold
APEX_PTHREAD_WRAPPER_STACK_SIZE 0 16k-8M When wrapping pthread_create, use this size for the stack.
APEX_PAPI_METRICS null space-delimited string of metric names List of metrics to be measured by APEX when timers are used. Only meaningful if APEX is configured with PAPI support. Any supported metric from papi_avail (see PAPI Documentation) can be used.
APEX_PAPI_SUSPEND 0 0,1 Suspend collection of PAPI metrics for APEX timers during the application execution