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Exercises and demos

Examples

Isolated

Load modules for Python, numpy (in SciPy-bundle), activate the environment, and install spacy on Kebnekaise at HPC2N

b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ module load GCC/11.3.0 OpenMPI/4.1.4 SciPy-bundle/2022.05 matplotlib/3.5.2
b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ source vpyenv/bin/activate
(vpyenv) b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ pip install --no-cache-dir --no-build-isolation spacy
  1. Installing seaborn. Using existing modules for numpy (in SciPy-bundle), matplotlib, and the vpyenv we created under Python 3.9.5. Note that you need to load Python again if you have been logged out, etc. but the virtual environment remains, of course

Load modules for Python, numpy (in SciPy-bundle), matplotlib, activate the environment, and install seaborn on Kebnekaise at HPC2N

b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ module load GCC/11.3.0 OpenMPI/4.1.4 SciPy-bundle/2022.05 matplotlib/3.5.2
b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ source vpyenv/bin/activate
(vpyenv) b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ pip install --no-cache-dir --no-build-isolation seaborn

Using the vpyenv created earlier and the spacy we installed under example 1) above.

Load modules for Python, numpy (in SciPy-bundle), activate the environment (on Kebnekaise at HPC2N)

b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ module load GCC/11.3.0 OpenMPI/4.1.4 SciPy-bundle/2022.05 matplotlib/3.5.2
b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ source vpyenv/bin/activate
(vpyenv) b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ python
Python 3.10.4 (main, Sep  21 2022, 11:17:12) [GCC 11.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import spacy
>>>

Interactive

Example, Kebnekaise, Requesting 4 cores for 30 minutes, then running Python

b-an01 [~]$ salloc -n 4 --time=00:30:00 -A hpc2nXXXX-YYY
salloc: Pending job allocation 20174806
salloc: job 20174806 queued and waiting for resources
salloc: job 20174806 has been allocated resources
salloc: Granted job allocation 20174806
salloc: Waiting for resource configuration
salloc: Nodes b-cn0241 are ready for job
b-an01 [~]$ module load GCC/11.3.0 OpenMPI/4.1.4 Python/3.10.4
b-an01 [~]$

Adding two numbers from user input (add2.py)

# This program will add two numbers that are provided by the user

# Get the numbers
a = int(input("Enter the first number: ")) 
b = int(input("Enter the second number: "))

# Add the two numbers together
sum = a + b

# Output the sum
print("The sum of {0} and {1} is {2}".format(a, b, sum))

Adding two numbers given as arguments (sum-2args.py)

import sys

x = int(sys.argv[1])
y = int(sys.argv[2])

sum = x + y

print("The sum of the two numbers is: {0}".format(sum))

Now for the examples:

Example, Kebnekaise, Running a Python script in the allocation we made further up. Notice that since we asked for 4 cores, the script is run 4 times, since it is a serial script

b-an01 [~]$ srun python sum-2args.py 3 4
The sum of the two numbers is: 7
The sum of the two numbers is: 7
The sum of the two numbers is: 7
The sum of the two numbers is: 7
b-an01 [~]$

Example, Running a Python script in the above allocation, but this time a script that expects input from you.

b-an01 [~]$ srun python add2.py 
2
3
Enter the first number: Enter the second number: The sum of 2 and 3 is 5
Enter the first number: Enter the second number: The sum of 2 and 3 is 5
Enter the first number: Enter the second number: The sum of 2 and 3 is 5
Enter the first number: Enter the second number: The sum of 2 and 3 is 5

Batch mode

Serial code

Running on Kebnekaise, SciPy-bundle/2021.05 and Python/3.9.5, serial code

#!/bin/bash
#SBATCH -A hpc2nXXXX-YYY # Change to your own after the course
#SBATCH --time=00:10:00 # Asking for 10 minutes
#SBATCH -n 1 # Asking for 1 core

# Load any modules you need, here for Python 3.10.4 and compatible SciPy-bundle
module load GCC/11.3.0 OpenMPI/4.1.4 Python/3.10.4 SciPy-bundle/2022.05

# Run your Python script 
python <my_program.py>

Serial code + self-installed package in virt. env.

Running on Kebnekaise, SciPy-bundle/2021.05, Python/3.9.5 + Python package you have installed yourself with virtual environment. Serial code

#!/bin/bash
#SBATCH -A hpc2nXXXX-YYY # Change to your own after the course
#SBATCH --time=00:10:00 # Asking for 10 minutes
#SBATCH -n 1 # Asking for 1 core

# Load any modules you need, here for Python 3.10.4 and compatible SciPy-bundle
module load GCC/11.3.0 OpenMPI/4.1.4 Python/3.10.4 SciPy-bundle/2022.05 

# Activate your virtual environment. Note that you either need to have added the location to your path, or give the full path
source <path-to-virt-env>/bin/activate

# Run your Python script 
python <my_program.py>

GPU code

Running on Kebnekaise, GCC/11.2.0 OpenMPI/4.1.1 SciPy-bundle/2021.10 TensorFlow/2.7.1, GPU code

#!/bin/bash
#SBATCH -A hpc2nXXXX-YYY # Change to your own after the course
#SBATCH --time=00:10:00 # Asking for 10 minutes
# Asking for one K80 card
#SBATCH --gres=gpu:k80:1

# Load any modules you need 
module load GCC/11.2.0 OpenMPI/4.1.1 SciPy-bundle/2021.10 TensorFlow/2.7.1

# Run your Python script 
python <my_tf_program.py>

The recommended TensorFlow version for this course is 2.7.1 on Kebnekaise. The module is compatible with Python 3.9.6 (automatically loaded when you load TensorFlow and its other prerequisites).

Machine Learning

We use PyTorch Tensors to fit a third order polynomial to a sine function. The forward and backward passes through the network are manually implemented.

# -*- coding: utf-8 -*-

import torch
import math

dtype = torch.float
device = torch.device("cpu")
# device = torch.device("cuda:0") # Uncomment this to run on GPU

# Create random input and output data
x = torch.linspace(-math.pi, math.pi, 2000, device=device, dtype=dtype)
y = torch.sin(x)

# Randomly initialize weights
a = torch.randn((), device=device, dtype=dtype)
b = torch.randn((), device=device, dtype=dtype)
c = torch.randn((), device=device, dtype=dtype)
d = torch.randn((), device=device, dtype=dtype)

learning_rate = 1e-6
for t in range(2000):
    # Forward pass: compute predicted y
    y_pred = a + b * x + c * x ** 2 + d * x ** 3

    # Compute and print loss
    loss = (y_pred - y).pow(2).sum().item()
    if t % 100 == 99:
        print(t, loss)

    # Backprop to compute gradients of a, b, c, d with respect to loss
    grad_y_pred = 2.0 * (y_pred - y)
    grad_a = grad_y_pred.sum()
    grad_b = (grad_y_pred * x).sum()
    grad_c = (grad_y_pred * x ** 2).sum()
    grad_d = (grad_y_pred * x ** 3).sum()

    # Update weights using gradient descent
    a -= learning_rate * grad_a
    b -= learning_rate * grad_b
    c -= learning_rate * grad_c
    d -= learning_rate * grad_d

print(f'Result: y = {a.item()} + {b.item()} x + {c.item()} x^2 + {d.item()} x^3')

This is an example of a batch script for running the above example, using PyTorch 1.10.0 and Python 3.9.5, running on GPUs.

Example batch script, running the above example on Kebnekaise (assuming it is named pytorch_fitting_gpu.py)

#!/bin/bash 
# Remember to change this to your own project ID after the course! 
#SBATCH -A hpc2nXXXX-YYY
# We are asking for 5 minutes
#SBATCH --time=00:05:00
# The following two lines splits the output in a file for any errors and a file for other output. 
#SBATCH --error=job.%J.err
#SBATCH --output=job.%J.out
# Asking for one K80
#SBATCH --gres=gpu:k80:1

# Remove any loaded modules and load the ones we need
module purge  > /dev/null 2>&1
module load GCC/10.3.0  OpenMPI/4.1.1 PyTorch/1.10.0-CUDA-11.3.1

srun python pytorch_fitting_gpu.py

TensorFlow

The example comes from https://machinelearningmastery.com/tensorflow-tutorial-deep-learning-with-tf-keras/ but there are also good examples at https://www.tensorflow.org/tutorials

We are using Tensorflow 2.7.1 and Python 3.9.6. Since there is no scikit-learn for these versions, we have to install that too:

Installing scikit-learn compatible with TensorFlow version 2.7.1 and Python version 3.9.6

We can now use scikit-learn in our example.

We will work with this example

# mlp for binary classification
from pandas import read_csv
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import LabelEncoder
from tensorflow.keras import Sequential
from tensorflow.keras.layers import Dense
# load the dataset
path = 'https://raw.githubusercontent.com/jbrownlee/Datasets/master/ionosphere.csv'
df = read_csv(path, header=None)
# split into input and output columns
X, y = df.values[:, :-1], df.values[:, -1]
# ensure all data are floating point values
X = X.astype('float32')
# encode strings to integer
y = LabelEncoder().fit_transform(y)
# split into train and test datasets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.33)
print(X_train.shape, X_test.shape, y_train.shape, y_test.shape)
# determine the number of input features
n_features = X_train.shape[1]
# define model
model = Sequential()
model.add(Dense(10, activation='relu', kernel_initializer='he_normal', input_shape=(n_features,)))
model.add(Dense(8, activation='relu', kernel_initializer='he_normal'))
model.add(Dense(1, activation='sigmoid'))
# compile the model
model.compile(optimizer='adam', loss='binary_crossentropy', metrics=['accuracy'])
# fit the model
model.fit(X_train, y_train, epochs=150, batch_size=32, verbose=0)
# evaluate the model
loss, acc = model.evaluate(X_test, y_test, verbose=0)
print('Test Accuracy: %.3f' % acc)
# make a prediction
row = [1,0,0.99539,-0.05889,0.85243,0.02306,0.83398,-0.37708,1,0.03760,0.85243,-0.17755,0.59755,-0.44945,0.60536,-0.38223,0.84356,-0.38542,0.58212,-0.32192,0.56971,-0.29674,0.36946,-0.47357,0.56811,-0.51171,0.41078,-0.46168,0.21266,-0.34090,0.42267,-0.54487,0.18641,-0.45300]
yhat = model.predict([row])
print('Predicted: %.3f' % yhat)

In order to run the above example, we will create a batch script and submit it.

Example batch script for Kebnekaise, TensorFlow version 2.7.1 and Python version 3.9.6, and the scikit-learn we installed above

#!/bin/bash 
# Remember to change this to your own project ID after the course! 
#SBATCH -A hpc2nXXXX-YYY
# We are asking for 5 minutes
#SBATCH --time=00:05:00
# Asking for one K80 
#SBATCH --gres=gpu:k80:1

# Remove any loaded modules and load the ones we need
module purge  > /dev/null 2>&1
module load module load GCC/11.2.0 OpenMPI/4.1.1 Python/3.9.6 SciPy-bundle/2021.10 TensorFlow/2.7.1

# Activate the virtual environment we installed to 
source <path-to-install-dir>/vpyenv/bin/activate 

# Run your Python script 
python <my_tf_program.py>

Submit with sbatch <myjobscript.sh>. After submitting you will (as usual) be given the job-id for your job. You can check on the progress of your job with squeue -u <username> or scontrol show <job-id>.

The output and errors will in this case be written to slurm-<job-id>.out.

General

You almost always want to run several iterations of your machine learning code with changed parameters and/or added layers. If you are doing this in a batch job, it is easiest to either make a batch script that submits several variations of your Python script (changed parameters, changed layers), or make a script that loops over and submits jobs with the changes.

Running several jobs from within one job

This example shows how you would run several programs or variations of programs sequentially within the same job:

Example batch script for Kebnekaise, TensorFlow version 2.7.1 and Python version 3.9.6)

#!/bin/bash 
# Remember to change this to your own project ID after the course! 
#SBATCH -A hpc2nXXXX-YYY
# We are asking for 5 minutes
#SBATCH --time=00:05:00
# Asking for one K80 
#SBATCH --gres=gpu:k80:1

# Remove any loaded modules and load the ones we need
module purge  > /dev/null 2>&1
module load module load GCC/11.2.0 OpenMPI/4.1.1 Python/3.9.6 SciPy-bundle/2021.10 TensorFlow/2.7.1

# Output to file - not needed if your job creates output in a file directly 
# In this example I also copy the output somewhere else and then run another executable (or you could just run the same executable for different parameters).

python <my_tf_program.py> <param1> <param2> > myoutput1 2>&1
cp myoutput1 mydatadir
python <my_tf_program.py> <param3> <param4> > myoutput2 2>&1
cp myoutput2 mydatadir
python <my_tf_program.py> <param5> <param6> > myoutput3 2>&1
cp myoutput3 mydatadir

GPU

Numba is installed as a module at HPC2N, but not in a version compatible with the Python we are using in this course (3.10.4), so we will have to install it ourselves. The process is the same as in the examples given for the isolated/virtual environment, and we will be using the virtual environment created earlier here. We also need numpy, so we are loading SciPy-bundle as we have done before:

Load Python 3.10.4 and its prerequisites + SciPy-bundle + CUDA, then activate the virtual environment before installing numba

b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ module load GCC/11.2.0 OpenMPI/4.1.1 Python/3.9.6 SciPy-bundle/2021.10 CUDA/11.7.0
b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ python -m venv --system-site-packages vpyenv
b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ source /proj/nobackup/support-hpc2n/bbrydsoe/vpyenv/bin/activate 
(vpyenv) b-an01 [/proj/nobackup/support-hpc2n/bbrydsoe]$ pip install --no-cache-dir --no-build-isolation numba
Collecting numba
  Downloading numba-0.56.0-cp39-cp39-manylinux2014_x86_64.manylinux_2_17_x86_64.whl (3.5 MB)
       ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 3.5/3.5 MB 38.7 MB/s eta 0:00:00
Requirement already satisfied: setuptools in /pfs/proj/nobackup/fs/projnb10/support-hpc2n/bbrydsoe/vpyenv/lib/python3.9/site-packages (from numba) (63.1.0)
Requirement already satisfied: numpy<1.23,>=1.18 in /cvmfs/ebsw.hpc2n.umu.se/amd64_ubuntu2004_bdw/software/SciPy-bundle/2021.05-foss-2021a/lib/python3.9/site-packages (from numba) (1.20.3)
Collecting llvmlite<0.40,>=0.39.0dev0
  Downloading llvmlite-0.39.0-cp39-cp39-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (34.6 MB)
       ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 34.6/34.6 MB 230.0 MB/s eta 0:00:00
Installing collected packages: llvmlite, numba
Successfully installed llvmlite-0.39.0 numba-0.56.0

[notice] A new release of pip available: 22.1.2 -> 22.2.2
[notice] To update, run: pip install --upgrade pip

Let us try using it. We are going to use the following program for testing (it was taken from https://linuxhint.com/gpu-programming-python/ but there are also many great examples at https://numba.readthedocs.io/en/stable/cuda/examples.html):

Python example using Numba

import numpy as np
from timeit import default_timer as timer
from numba import vectorize

# This should be a substantially high value.
NUM_ELEMENTS = 100000000

# This is the CPU version.
def vector_add_cpu(a, b):
  c = np.zeros(NUM_ELEMENTS, dtype=np.float32)
  for i in range(NUM_ELEMENTS):
      c[i] = a[i] + b[i]
  return c

# This is the GPU version. Note the @vectorize decorator. This tells
# numba to turn this into a GPU vectorized function.
@vectorize(["float32(float32, float32)"], target='cuda')
def vector_add_gpu(a, b):
  return a + b;

def main():
  a_source = np.ones(NUM_ELEMENTS, dtype=np.float32)
  b_source = np.ones(NUM_ELEMENTS, dtype=np.float32)

  # Time the CPU function
  start = timer()
  vector_add_cpu(a_source, b_source)
  vector_add_cpu_time = timer() - start

  # Time the GPU function
  start = timer()
  vector_add_gpu(a_source, b_source)
  vector_add_gpu_time = timer() - start

   # Report times
   print("CPU function took %f seconds." % vector_add_cpu_time)
   print("GPU function took %f seconds." % vector_add_gpu_time)

   return 0

if __name__ == "__main__":
  main()

As before, we need a batch script to run the code. There are no GPUs on the login node.

Batch script to run the numba code (add-list.py) at Kebnekaise

#!/bin/bash
# Remember to change this to your own project ID after the course!
#SBATCH -A hpc2nXXXX-YYY
# We are asking for 5 minutes
#SBATCH --time=00:05:00
# Asking for one K80
#SBATCH --gres=gpu:k80:1

# Remove any loaded modules and load the ones we need
module purge  > /dev/null 2>&1
module load GCC/11.2.0 OpenMPI/4.1.1 Python/3.9.6 SciPy-bundle/2021.10 CUDA/11.7.0

# Activate the virtual environment we installed to
source /proj/nobackup/support-hpc2n/bbrydsoe/vpyenv/bin/activate

# Run your Python script
python add-list.py

As before, submit with sbatch add-list.sh (assuming you called the batch script thus - change to fit your own naming style).

Numba example 2

An initial implementation of the 2D integration problem with the CUDA support for Numba could be as follows:

integration2d_gpu.py

from __future__ import division
from numba import cuda, float32
import numpy
import math
from time import perf_counter

# grid size
n = 100*1024
threadsPerBlock = 16
blocksPerGrid = int((n+threadsPerBlock-1)/threadsPerBlock)

# interval size (same for X and Y)
h = math.pi / float(n)

@cuda.jit
def dotprod(C):
    tid = cuda.threadIdx.x + cuda.blockIdx.x * cuda.blockDim.x 

    if tid >= n:
        return

    #cummulative variable
    mysum = 0.0
    # fine-grain integration in the X axis
    x = h * (tid + 0.5)
    # regular integration in the Y axis
    for j in range(n):
        y = h * (j + 0.5)
        mysum += math.sin(x + y)

    C[tid] = mysum


# array for collecting partial sums on the device
C_global_mem = cuda.device_array((n),dtype=numpy.float32)

starttime = perf_counter()
dotprod[blocksPerGrid,threadsPerBlock](C_global_mem)
res = C_global_mem.copy_to_host()
integral = h**2 * sum(res)
endtime = perf_counter()

print("Integral value is %e, Error is %e" % (integral, abs(integral - 0.0)))
print("Time spent: %.2f sec" % (endtime-starttime))

The time for executing the kernel and doing some postprocessing to the outputs (copying the C array and doing a reduction) was 4.35 sec. which is a much smaller value than the time for the serial numba code of 152 sec.

Notice the larger size of the grid in the present case (100*1024) compared to the serial case's size we used previously (10000). Large computations are necessary on the GPUs to get the benefits of this architecture.

One can take advantage of the shared memory in a thread block to write faster code. Here, we wrote the 2D integration example from the previous section where threads in a block write on a shared[] array. Then, this array is reduced (values added) and the output is collected in the array C. The entire code is here:

integration2d_gpu_shared.py

from __future__ import division
from numba import cuda, float32
import numpy
import math
from time import perf_counter

# grid size
n = 100*1024
threadsPerBlock = 16
blocksPerGrid = int((n+threadsPerBlock-1)/threadsPerBlock)

# interval size (same for X and Y)
h = math.pi / float(n)

@cuda.jit
def dotprod(C):
    # using the shared memory in the thread block
    shared = cuda.shared.array(shape=(threadsPerBlock), dtype=float32) 

    tid = cuda.threadIdx.x + cuda.blockIdx.x * cuda.blockDim.x 
    shrIndx = cuda.threadIdx.x

    if tid >= n:
        return

    #cummulative variable
    mysum = 0.0
    # fine-grain integration in the X axis
    x = h * (tid + 0.5)
    # regular integration in the Y axis
    for j in range(n):
        y = h * (j + 0.5)
        mysum += math.sin(x + y)

    shared[shrIndx] = mysum

    cuda.syncthreads()

    # reduction for the whole thread block
    s = 1
    while s < cuda.blockDim.x:
        if shrIndx % (2*s) == 0:
            shared[shrIndx] += shared[shrIndx + s]
        s *= 2
        cuda.syncthreads()
    # collecting the reduced value in the C array
    if shrIndx == 0:
        C[cuda.blockIdx.x] = shared[0]

# array for collecting partial sums on the device
C_global_mem = cuda.device_array((blocksPerGrid),dtype=numpy.float32)

starttime = perf_counter()
dotprod[blocksPerGrid,threadsPerBlock](C_global_mem)
res = C_global_mem.copy_to_host()
integral = h**2 * sum(res)
endtime = perf_counter()

print("Integral value is %e, Error is %e" % (integral, abs(integral - 0.0)))
print("Time spent: %.2f sec" % (endtime-starttime))

We need a batch script to run this Python code, an example script is here:

#!/bin/bash
#SBATCH -A project_ID
#SBATCH -t 00:05:00
#SBATCH -N 1
#SBATCH -n 28
#SBATCH -o output_%j.out   # output file
#SBATCH -e error_%j.err    # error messages
#SBATCH --gres=gpu:k80:2
#SBATCH --exclusive

ml purge > /dev/null 2>&1
ml GCCcore/11.2.0 Python/3.9.6
ml GCC/11.2.0 OpenMPI/4.1.1
ml CUDA/11.7.0

virtualenv --system-site-packages /proj/nobackup/<your-project-storage>/vpyenv-python-course
source /proj/nobackup/<your-project-storage>/vpyenv-python-course/bin/activate

python integration2d_gpu.py

The simulation time for this problem's size was 1.87 sec.

Exercises

Run the first serial example from further up on the page for this short Python code (sum-2args.py)

import sys

x = int(sys.argv[1])
y = int(sys.argv[2])

sum = x + y

print("The sum of the two numbers is: {0}".format(sum))

Remember to give the two arguments to the program in the batch script.

This is for Kebnekaise. Adding the numbers 2 and 3.

#!/bin/bash
#SBATCH -A hpc2nXXXX-YYY # Change to your own after the course
#SBATCH --time=00:05:00 # Asking for 5 minutes
#SBATCH -n 1 # Asking for 1 core

# Load any modules you need, here for Python 3.9.6
module load GCC/11.2.0  OpenMPI/4.1.1 Python/3.9.6

# Run your Python script 
python sum-2args.py 2 3