oneapi-src / oneapi-src/oneAPI-samples
OpenMP offload performance is worse than sequential CPU performance
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Descripción
Summary
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factors are considered important to reproduce an issue.
The time taken to complete calculation of pi using sequential CPU execution is better than OpenMP CPU and OpenMP GPU
Version
Report oneAPI Toolkit version and oneAPI Sample version or hash.
Samples commit id: 4bed52e76ceb17243a0bc4ce24e9aed52aaa6e49
Environment
Provide OS information and hardware information if applicable.
Ubuntu 20.04
11th Gen Intel(R) Core(TM) i7-1185GRE @ 2.80GHz
Steps to reproduce
Please check that the issue is reproducible with the latest revision on
master. Include all the steps to reproduce the issue.
build and run the openmp reduction sample.
Observed behavior
Document behavior you observe. For performance defects, like performance
regressions or a function being slow, provide a log if possible.
observe the time taken by each and notice that openmp offload performs the worst.
Expected behavior
Document behavior you expect.
OpenMP offload should perform better.
Verified Fix
Increase the number of steps by a factor of 100 and the time taken for each lines up according to expectations. OpenMP offload better than OpenMP CPU better than Seq CPU. We do not want developers to be presented with a poorly performing offload to begin with. The alternative is mention this in the README or perhaps do both. Increase num_steps and add some detail to the README. It will also be good to add the num_steps as a tunable parameter with a default value so developer can play with it.
Guía de contribución
Primeros pasos
- Lee el issue completo y luego la guía de contribución del proyecto.
- Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
- Haz un fork del repositorio y trabaja en una rama.
- Abre un pull request que haga referencia al número del issue.
Línea de trabajo
Comienza con el openmp reduction sample y compara las rutas de ejecución de la CPU secuencial, la CPU con OpenMP y la GPU con OpenMP utilizando el entorno de Ubuntu y CPU Intel indicado. Revisa el README y el manejo actual de num_steps; se considerará terminado cuando el sample predeterminado no muestre de forma engañosa un bajo rendimiento de offload y estén documentados el parámetro ajustable y el contexto de rendimiento.
Escrito por el modelo de indexación a partir del texto del issue.
Evaluación
- Stack tecnológico
- cpp
- Área
- performance
- Tipo de issue
- Error
- Dificultad
- 3/5
- Tiempo estimado
- 1-2 días
- Estado de actividad
- Estancado
- Claridad
- Bastante claro
- Aptitud para principiantes
- 35/100