Hello World

Write a simple ex1_hello_world.cu application using cuda. Experiment with different amount of blocks and threads per block.

#include <stdio.h>

__global__ void print_from_gpu(void) {
    int tidx = blockIdx.x*blockDim.x+threadIdx.x;
    printf("Hello from device! My threadId = blockIdx.x *blockDim.x + threadIdx.x <=> %d = %d * %d + %d \n",
    tidx, blockIdx.x, blockDim.x, threadIdx.x);
}

int main(void) {
    printf("Hello World from host!\n");

    print_from_gpu<<<2,3>>>();  // <<<blocks, threads_per_block>>>

    cudaDeviceSynchronize();
    return 0;
}

Compile and run:

$ nvcc ex1_hello_world.cu -o hello_world
$ ./hello_world

If you have an account at ICM HPC, you can use the Rysy cluster to run GPU jobs:

ssh username@hpc.icm.edu.pl
ssh rysy
# run interactive session
srun -N1 -n4 --account=GRANT_NAME --gres=gpu:1 --time=01:00:00 --pty /bin/bash -l
# prepare enviroment
module load gpu/cuda/11.1

Or schedule the job to the queue:

#!/bin/bash -l
#SBATCH -J gpu_test
#SBATCH --gres=gpu:1
#SBATCH --cpus-per-task=1
#SBATCH --ntasks-per-node=1
#SBATCH --nodes=1 
#SBATCH --account=GRANT_NAME
#SBATCH --time=01:00:00 
#SBATCH --qos=normal


module load gpu/cuda/11.1  
cd /home/$USER/rysy/folder_with_your_cuda_exercises
nvcc ex1_hello_world.cu -o ex1_hello_world
srun ex1_hello_world

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Last update: December 15, 2020