Update cuda.md

Author: T-Almeida

docs/detail_material/cuda.md

@@ -1 +1,75 @@
+# Cuda example
+
+This example shows how you can compile and run a cuda program in one of the clusters GPU nodes. We expected that you already have access and know how to login.
+
+## 0. Git clone the guides repo with the examples
+
+To facilitate the demonstration we already prepared the code and scripts necessary, your job is to first run and then understand by looking into more detail.
+
+```bash
+$ git clone https://github.com/ieeta-pt/HPC-guides.git
+$ cd HPC-guides/examples/cuda
+```
+
+## 1. Preprare the environment
+
+First step is the preparation of the development enviroment which in this case would be to load the gcc compiler and CUDA libraries.
+
+```bash
+$ module load gcc/11
+$ module load cuda
+```
+
+Here we load gcc 11 and not 12, since the currently installed CUDA version (11.8) advises to run with gcc 11.
+
+## 2. Compile the cuda program
+
+For compiling the cuda program just call the nvcc
+
+```bash
+$ nvcc vector_addition.cu -o vector_addition
+```
+
+## 3. Submit the job
+
+`lunch_cuda.sh` already contains the code to lunch the slurm job while requesting a gpu.
+
+```bash
+$ sbatch lunch_cuda.sh
+```
+
+Check your directly for the output file and cat:
+
+```bash
+$ ll
+total 808
+drwxr-xr-x 2 tiagoalmeida students   4096 Jul  5 15:49 ./
+drwxr-xr-x 3 tiagoalmeida students   4096 Jul  5 15:48 ../
+-rw-r--r-- 1 tiagoalmeida students    248 Jul  5 15:49 Cuda-93.out
+-rw-r--r-- 1 tiagoalmeida students    504 Jul  5 15:48 lunch_cuda.sh
+-rwxr-xr-x 1 tiagoalmeida students 803936 Jul  5 15:48 vector_addition*
+-rw-r--r-- 1 tiagoalmeida students   2051 Jul  5 15:48 vector_addition.cu
+```
+
+```bash
+$ cat Cuda-93.out 
+Job Information for Job ID: 93 from tiagoalmeida
+------------ ------------
+Account: students
+CPUs per Node: 2
+GPU: NVIDIA RTX A2000
+Partition: gpu
+QOS: normal
+Start Time: 2024-07-05 14:49:32 UTC
+Running On Node: dl-srv-02
+------------ ------------
+
+---------------------------
+__SUCCESS__
+---------------------------
+N                 = 1048576
+Threads Per Block = 256
+Blocks In Grid    = 4096
+---------------------------
+```