Guided Works similar to dynamic scheduling, but it orders the chunks of  work from the largest to the smallest, which can handle imbalances  more properly. By default, the chunk size is calculated by  loop_count  divided by  number_of_threads . Auto The compiler decides between static, dynamic, and guided. Runtime Use the  OMP_SHEDULE  environment variable. The advantage of this  scheduler is that rewriting or recompiling the source code is  unnecessary. Type of scheduling Description OpenMP applications are often written so that they can create an arbitrary number of threads.  In this case, the user sets the  OMP_NUM_THREADS  environment variable to specify the number of  threads to create. For example, to run the application with 20 threads, use this command: export OMP_NUM_THREADS=20 Again, the application can control the scheduling policy from the source code, as shown in the  following example: #pragma omp parallel ... num_threads(4) Specifying the number of OpenMP threads The OpenMP 4.5 standard introduced the  OMP_DISPLAY_ENV  environment variable to display  the OpenMP version and list the internal control variables (ICVs). The OpenMP run time  prints data to the  stderr  output stream. If the user sets the value to  TRUE , the OpenMP  version number and initial values of ICVs are printed.  The  VERBOSE  value instructs the OpenMP run time to augment the output with the values of  vendor-specific variables. If the value of this environment variable is set to  FALSE  or undefined,  no information is printed. This variable is useful when you must be certain that the runtime  environment is configured as expected at the moment that the program loads. The POWER9 processor can handle multiple hardware threads simultaneously. With the  increasing number of logical processors, the operating system (OS) kernel scheduler has  more possibilities for automatic load balancing. For technical computing workloads, the fixed  position of threads within the server is typically preferred. The IDs of the logical processors are zero-based. Each logical processor has the same index,  regardless of the simultaneous multithreading (SMT) mode. Logical processors are counted  starting from the first core of the first socket. The first logical processor of the second core  features the index 4. Number the logical processors of the second socket only after you finish  the numbering of the logical processors of the first socket. Chapter 8. Running parallel software, performance enhancement, and scalability testing  229 Placement of OpenMP threads Showing OpenMP data