update exerciseC

exercises/exerciseC/plot.py

@@ -1,67 +1,53 @@
-import sys
+import os
-import collections
 import numpy as np
+import matplotlib.pyplot as plt
+import matplotlib.patheffects as PathEffects
 
-dts = collections.defaultdict(dict)
+N_processes = 5
+N_threads = 5
 
-for fname in sys.argv[1:]:
+# Load measured timings
-    values = open(fname).read().split()
+times = np.empty((N_processes, N_threads))
-    n1 = int(values[0])
+for fname in os.listdir('timings'):
-    n2 = int(values[1])
+    values = open(f'timings/{fname}').read().split()
+    n_processes = int(values[0])
+    n_threads = int(values[1])
     dt = float(values[2])
+    times[n_processes-1][n_threads-1] = dt
+print(times)
 
-    dts[n1][n2] = dt
+""" Plot measured time"""
+fig_time, axs_time = plt.subplots()
+im = axs_time.imshow(times.T, origin='lower')
+axs_time.set_title('Computation time')
+fig_time.colorbar(im, ax=axs_time, label='Measured computation time (s)')
 
-print(dts)
+""" Plot speedup """
-N1 = max(dts)
+workers = np.arange(N_processes + 1)[:, None] * np.arange(N_threads + 1)
-N2 = max(max(v) for v in dts.values())
+speedup = times[0, 0] / times
 
-print(N1, N2)
+fig_speedup, axs_speedup = plt.subplots()
+im = axs_speedup.imshow(speedup.T, origin='lower')
+axs_speedup.set_title('Computation speed-up')
+fig_speedup.colorbar(im, ax=axs_speedup, label='Speed-up')
 
-x = np.empty((N1 + 1, N2 + 1))
+# Set same style for both plots
-for n1, values in dts.items():
+for axs, data in zip([axs_time, axs_speedup], [times, speedup]):
-    for n2, v in values.items():
+    axs.set_xlabel('# processes')
-        x[n1, n2] = v
+    axs.set_ylabel('# threads')
+    axs.set_xticks(np.arange(N_processes))
+    axs.set_xticklabels(np.arange(N_processes)+1)
+    axs.set_yticks(np.arange(N_threads))
+    axs.set_yticklabels(np.arange(N_threads)+1)
 
-x[:, 0] = np.nan
+    for i in range(N_processes):
-x[0, :] = np.nan
+        for j in range(N_threads):
+            txt = axs.text(i, j, f'{data[i, j]:.2f}', fontsize=10, color='w',
+                        ha='center', va='center', fontweight='bold')
+            txt.set_path_effects([PathEffects.withStroke(linewidth=0.5, foreground='k')])
+    axs.spines[['right', 'top']].set_visible(False)
 
-print(x)
+# Save plots
+fig_time.savefig('time.png', dpi=300)
+fig_speedup.savefig('speedup.png', dpi=300)
 
-from matplotlib import pyplot
-
-fig, axes = pyplot.subplots()
-im = axes.imshow(x, origin='lower')
-axes.set_ylabel('# processes')
-axes.set_xlabel('# threads')
-axes.spines[['right', 'top']].set_visible(False)
-axes.set_title('time')
-fig.colorbar(im, ax=axes, label='s')
-
-fig_small, axes = pyplot.subplots()
-im = axes.imshow(x[:5, :5], origin='lower')
-axes.set_ylabel('# processes')
-axes.set_xlabel('# threads')
-axes.spines[['right', 'top']].set_visible(False)
-axes.set_title('time')
-fig_small.colorbar(im, ax=axes, label='s')
-
-workers = np.arange(N1 + 1)[:, None] * np.arange(N2 + 1)
-speedup = x[1,1] / x
-
-speedup[:, 0] = np.nan
-speedup[0, :] = np.nan
-
-figs, axes = pyplot.subplots()
-im = axes.imshow(speedup, origin='lower')
-axes.set_ylabel('# processes')
-axes.set_xlabel('# threads')
-axes.spines[['right', 'top']].set_visible(False)
-axes.set_title('speedup')
-figs.colorbar(im, ax=axes, label='s')
-
-fig.savefig('time.svg')
-fig_small.savefig('time_inset.svg')
-figs.savefig('speedup.svg')
-
-pyplot.show()

exercises/exerciseC/process_images.py

@@ -3,17 +3,11 @@ import sys
 from multiprocessing import Pool as ProcessPool
 import time
 
-def process_image(fname):
+def process_image(input_tuple):
-    n_threads = os.getenv('OMP_NUM_THREADS', '(unset)')
-    print(f"Worker {fname=} OMP_NUM_THREADS={n_threads}")
 
-    # An image is an array with width, height and three (RGB) color channels
+    fname, A = input_tuple
-    # (Sometimes there is a transparency channel too: RGBA)
+    n_threads = os.getenv('OMP_NUM_THREADS', '(unset)')
-    im = Image.open(fname)
+    print(f"Worker {fname=} OMP_NUM_THREADS={n_threads}", flush=True)
-    try:
-        A = np.median(im, axis=2)[::4, ::4]
-    except:
-        A = np.array(im)[::4, ::4]
 
     # Decompose image
     U, S, Vh = np.linalg.svd(A)
@@ -36,10 +30,10 @@ if __name__ == '__main__':
     fnames = sys.argv[3:]
 
     # Check that the output folders exist, or create them if needed
-    if not os.path.isdir('processed_images'): os.mkdir('processed_images')
     if not os.path.isdir('timings'): os.mkdir('timings')
+    if not os.path.isdir('processed_images'): os.mkdir('processed_images')
 
-    print(f"Controller with {n_processes} processes and {n_threads} threads / worker")
+    print(f"Controller with {n_processes} processes and {n_threads} threads / worker", flush=True)
 
     # The environment that is set in the parent is inherited by child workers,
     # we need to set the variable before numpy is imported!
@@ -50,19 +44,28 @@ if __name__ == '__main__':
     import numpy as np
     from PIL import Image
 
-    # Time the execution
+    # I/O Load the images
+    image_arrays = []
+    for fname in fnames:
+        im = Image.open(fname)
+        A = np.array(im)
+        image_arrays.append((fname, A))
+
+    # Time the execution of the pool map
     start_time = time.time()
     with ProcessPool(n_processes) as p:
-        new_images = p.map(process_image, fnames)
+        new_images = p.map(process_image, image_arrays)
     elapsed_time = time.time() - start_time
 
+    # I/O save the processed images
     for im, fname in zip(new_images, fnames):
         im = Image.fromarray(im)
         im.save(fname.replace('images', 'processed_images'))
 
-    print(f'{n_processes} processes and {n_threads} threads and {len(fnames)} jobs: {elapsed_time}')
+    print(f'{n_processes} processes and {n_threads} threads and {len(fnames)} jobs: {elapsed_time}\n',
+          flush=True)
 
-    # IO: Save the timing to a unique txt file
+    # I/O: Save the timing to a unique txt file
     filename = f'timings/{n_processes:02}_processes_{n_threads:02}_threads.txt'
     with open(filename, 'w') as file:
         file.write(f'{n_processes} {n_threads} {elapsed_time:.6f}')

exercises/exerciseC/run_with_all_configurations.sh

@@ -1,7 +1,8 @@
-# This is bash, it executes the python script multiple times
+# This is bash
-for i in {1..10}
+# It runs the python script multiple times with different arguments
+for i in {1..5}  # Number of processes
 do
-    for j in {1..10}
+    for j in {1..5}  # Number of threads
     do
         python process_images.py $i $j images/*
     done