| .. _smp_pi: |
| |
| SMP Pi |
| ########### |
| |
| Overview |
| ******** |
| This sample application calculates Pi independently in many threads, and |
| demonstrates the benefit of multiple execution units (CPU cores) |
| when compute-intensive tasks can be run in parallel, with |
| no cross-dependencies or shared resources. |
| |
| By changing the value of CONFIG_MP_MAX_NUM_CPUS on SMP systems, you |
| can see that using more cores takes almost linearly less time |
| to complete the computational task. |
| |
| You can also edit the sample source code to change the |
| number of digits calculated (``DIGITS_NUM``), and the |
| number of threads to use (``THREADS_NUM``). |
| |
| Building and Running |
| ******************** |
| |
| This project outputs Pi values calculated by each thread and in the end total time |
| required for all the calculation to be done. It can be built and executed |
| on Synopsys ARC HSDK board as follows: |
| |
| .. zephyr-app-commands:: |
| :zephyr-app: samples/smp/pi |
| :host-os: unix |
| :board: qemu_x86_64 |
| :goals: run |
| :compact: |
| |
| Sample Output |
| ============= |
| |
| .. code-block:: console |
| |
| Calculate first 240 digits of Pi independently by 16 threads. |
| Pi value calculated by thread #0: 3141592653589793238462643383279502884197... |
| Pi value calculated by thread #1: 3141592653589793238462643383279502884197... |
| ... |
| Pi value calculated by thread #14: 314159265358979323846264338327950288419... |
| Pi value calculated by thread #15: 314159265358979323846264338327950288419... |
| All 16 threads executed by 4 cores in 28 msec |
