OpenACC Tutorial - Adding directives: Difference between revisions

OpenACC Tutorial - Adding directives (view source)

Revision as of 21:53, 9 December 2022

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Here will be the introduction to NVVP

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-The results are correct. However, not only do we not get any speed up, but we rather get a slow down by a factor of almost 4! Let's profile the code again using NVidia's visual profiler (<tt>nvvp</tt>). This can be done with the following steps:
+The results are correct. However, not only do we not get any speed up, but we rather get a slow down by a factor of almost 4! Let's profile the code again using NVidia's visual profiler (<tt>nvvp</tt>).
+=== NVIDIA Visual Profiler ===
+[[File:Nvvp-pic0.png|thumbnail|300px|NVVP profiler|right]]
+[[File:Nvvp-pic1.png|thumbnail|300px|Browse for the executable you want to profile|right]]
+One graphical profiler available for OpenACC applications is the
+[https://developer.nvidia.com/nvidia-visual-profiler NVIDIA Visual Profiler (NVVP)].
+It's a cross-platform analyzing tool '''for codes written with OpenACC and CUDA C/C++ instructions'''.
+Consequently, if the executable is not using the GPU, you will get no result from this profiler.
+When [[Visualization/en#Remote_windows_with_X11-forwarding|X11 is forwarded to an X-Server]], or when using a [[VNC|Linux desktop environment]] (also via [[JupyterHub#Desktop|JupyterHub]] with two (2) CPU cores, 5000M of memory and one (1) GPU),
+it is possible to launch the NVVP from a terminal:
+</translate>
+{{Command
+|module load cuda/11.7 java/1.8
+}}
+{{Command
+|nvvp
+}}
+<translate>
+# After the NVVP startup window, you get prompted for a ''Workspace'' directory, which will be used for temporary files. Replace <code>home</code> with <code>scratch</code> in the suggested path. Then click ''OK''.
+# Select ''File > New Session'', or click on the corresponding button in the toolbar.
+# Click on the ''Browse'' button at the right of the ''File'' path editor.
+## Change directory if needed.
+## Select an executable built from codes written with OpenACC and CUDA C/C++ instructions.
+# Below the ''Arguments'' editor, select the profiling option ''Profile current process only''.
+# Click ''Next >'' to review additional profiling options.
+# Click ''Finish'' to start profiling the executable.
+This can be done with the following steps:
 # Start <tt>nvvp</tt> with the command <tt>nvvp &</tt>   (the <tt>&</tt> sign is to start it in the background)
 # Go in File -> New Session