diff --git a/lab_2/10_answer.md b/lab_2/10_answer.md new file mode 100644 index 0000000..ae0d5c4 --- /dev/null +++ b/lab_2/10_answer.md @@ -0,0 +1,8 @@ +# How many steps m you can run the program? +The limit is somewhere between m=6300000 m=6400000 on my laptop + +# How do you recognize that the system is running out of memory? +The memory and swap gets filled up and the process gets killed by systemd-oomd + +# Plot the runtime +See 10_runtime_plot.png diff --git a/lab_2/10_memleak/Makefile b/lab_2/10_memleak/Makefile new file mode 100644 index 0000000..0ef13b8 --- /dev/null +++ b/lab_2/10_memleak/Makefile @@ -0,0 +1,18 @@ +binary = memleak +folder = memleak +objects = $(patsubst %.cpp,%.o,$(wildcard *.cpp)) + +run: $(binary) + ./$(binary) 7 100000000 + +$(binary): $(objects) + g++ -o $@ $^ + +clean: + rm -f *.o + +clear: clean + rm -f *.zip $(binary) + +zip: clean + zip $(folder) Makefile *.cpp *.h diff --git a/lab_2/10_memleak/chain-random-walk.cpp b/lab_2/10_memleak/chain-random-walk.cpp new file mode 100644 index 0000000..780b048 --- /dev/null +++ b/lab_2/10_memleak/chain-random-walk.cpp @@ -0,0 +1,78 @@ +#include +#include +#include + +#include "chain-random-walk.h" + +using namespace crw; + +namespace { + // set each element forward or backward by 1, at random + void stochastic_unit_step(long size, float config[]) + { + for(long i = 0; i < size; i++) + if(std::rand() % 2 == 0) config[i]++; + else config[i]--; + } + + void shift_centre_to_origin(long size, float config[]) + { + double sum = 0.0; + for(long i = 0; i < size; i++) sum += config[i]; + for(long i = 0; i < size; i++) config[i] -= sum/size; + } + + const int el_out_max = 9; // show at most the first nine elements +} + +float crw::elongation(long size, float config[]) +{ + float min = config[0]; + float max = config[0]; + + for(long i = 1; i < size; i++) + if(config[i] > max) max = config[i]; + else if(config[i] < min) min = config[i]; + + return max - min; +} + +float* crw::step(long size, float previous[]) +{ + // allocate the next configuration + float* config = new float[size](); + + // first, let the chain contract: each element is attracted by its neighbours + for(long i = 0; i < size; i++) + config[i] = 0.5*previous[i] + 0.25*previous[(i-1) % size] + + 0.25*previous[(i+1) % size]; + + stochastic_unit_step(size, config); // actual random walk step + shift_centre_to_origin(size, config); // shift such that the average remains zero + + return config; +} + +void crw::output(long no, long size, float present[], float extreme[], double avg_el) +{ + /* output statistics over the run so far + */ + std::cout << std::setw(12) << no << "\t" << std::setprecision(3) << std::fixed + << std::setw(6) << elongation(size, present) << " " + << std::setprecision(7) << std::setw(10) << avg_el << " " << std::setprecision(5) + << std::setw(9) << elongation(size, extreme) << std::setprecision(3) << "\t\t"; + + /* display the present configuration, showing up to element coordinates */ + for(long i = 0; (i < size) && (i < el_out_max); i++) + std::cout << std::setw(7) << present[i] << " "; + if(size > el_out_max) std::cout << "..."; + std::cout << "\t\t"; + + /* display the most extreme configuration so far, + * showing up to element coordinates + */ + for(long i = 0; (i < size) && (i < el_out_max); i++) + std::cout << std::setw(7) << extreme[i] << " "; + if(size > el_out_max) std::cout << "..."; + std::cout << "\n"; +} diff --git a/lab_2/10_memleak/chain-random-walk.h b/lab_2/10_memleak/chain-random-walk.h new file mode 100644 index 0000000..9ad3d0e --- /dev/null +++ b/lab_2/10_memleak/chain-random-walk.h @@ -0,0 +1,11 @@ +#ifndef CHAIN_RANDOM_WALK_H +#define CHAIN_RANDOM_WALK_H + +namespace crw +{ + float elongation(long size, float config[]); + float* step(long size, float previous[]); + void output(long no, long size, float present[], float extreme[], double avg_el); +} + +#endif diff --git a/lab_2/10_memleak/const_Nm_timings.csv b/lab_2/10_memleak/const_Nm_timings.csv new file mode 100644 index 0000000..3417d6c --- /dev/null +++ b/lab_2/10_memleak/const_Nm_timings.csv @@ -0,0 +1,10 @@ +1024, 43.46 +512, 44.03 +256, 45.26 +128, 46.54 +64, 47.82 +32, 50.89 +16, 56.13 +8, 60.42 +4, 59.66 +2, 56.71 \ No newline at end of file diff --git a/lab_2/10_memleak/const_m_timings.csv b/lab_2/10_memleak/const_m_timings.csv new file mode 100644 index 0000000..a1f2a8b --- /dev/null +++ b/lab_2/10_memleak/const_m_timings.csv @@ -0,0 +1,10 @@ +1024, 43.84 +512, 22.24 +256, 11.32 +128, 5.86 +64, 3.05 +32, 1.61 +16, 0.89 +8, 0.47 +4, 0.24 +2, 0.15 diff --git a/lab_2/10_memleak/memleak.cpp b/lab_2/10_memleak/memleak.cpp new file mode 100644 index 0000000..89b57b9 --- /dev/null +++ b/lab_2/10_memleak/memleak.cpp @@ -0,0 +1,62 @@ +#include +#include +#include + +#include "chain-random-walk.h" + +namespace { + constexpr int default_size = 7; + constexpr int default_steps = 100000000; + constexpr int outlines = 25; +} + +/* first argument: array size + * second argument: number of steps + */ +int main(int argc, char** argv) +{ + long size = default_size; + if(argc > 1) size = std::atol(argv[1]); + assert(size > 0); + + long steps = default_steps; + if(argc > 2) steps = std::atol(argv[2]); + assert(steps > 0); + + long outfreq = steps / outlines; + if(outfreq < 1) outfreq = 1; + + /* the configuration is given by an array of float numbers */ + float* present_configuration = new float[size](); + + /* store the one with greatest deviation between min and max element */ + float* extreme_configuration = present_configuration; + float extreme_elongation = 0.0; + double el_sum = 0.0; + double el_avg = 0.0; + + std::srand(std::time(nullptr)); // initialize the random number generator + + for(long i = 0; i < steps; i++) + { + if(i % outfreq == 0) + crw::output(i, size, present_configuration, extreme_configuration, el_avg); + + /* here we are calling the random walk step; + * this returns a new configuration (float array) on the heap + */ + present_configuration = crw::step(size, present_configuration); + float present_elongation = crw::elongation(size, present_configuration); + + if(present_elongation > extreme_elongation) + { + extreme_configuration = present_configuration; + extreme_elongation = present_elongation; + } + el_sum += present_elongation; + el_avg = el_sum / (i + 1.0); + } + crw::output(steps, size, present_configuration, extreme_configuration, el_avg); + + delete[] present_configuration; +} diff --git a/lab_2/10_memleak/plot.py b/lab_2/10_memleak/plot.py new file mode 100644 index 0000000..14f6332 --- /dev/null +++ b/lab_2/10_memleak/plot.py @@ -0,0 +1,34 @@ +import matplotlib.pyplot as plt +import matplotlib.cbook as cbook + +import numpy as np +import pandas as pd + +f = open('const_m_timings.csv', 'r') +x1 = [] +y1 = [] +for l in f.readlines(): + l = l.split(',') + x1.append(l[0]) + y1.append(float(l[1])) + +f = open('const_Nm_timings.csv', 'r') +x2 = [] +y2 = [] +for l in f.readlines(): + l = l.split(',') + x2.append(l[0]) + y2.append(float(l[1])) + +plt.plot(x1, y1, label = 'constant m') +plt.plot(x2, y2, label = 'constant Nm') +for i in range(len(x1)): + plt.text(i,y1[i],str(y1[i])+'s') +for i in range(len(x2)): + plt.text(i,y2[i],str(y2[i])+'s') +plt.title('runtime t as a function of number of steps N') +plt.xlabel('N') +plt.ylabel('time (s)') +plt.grid() +plt.legend() +plt.show() diff --git a/lab_2/10_memleak/time_Nm.nu b/lab_2/10_memleak/time_Nm.nu new file mode 100644 index 0000000..7ecab01 --- /dev/null +++ b/lab_2/10_memleak/time_Nm.nu @@ -0,0 +1,6 @@ +for x in [1024 512 256 128 64 32 16 8 4 2] { +$x | into string | save --append log.csv; +", " | save --append log.csv; +let m = 2048000000 / $x; +time -f %e -a -o log.csv ./memleak $x $m; +}; \ No newline at end of file diff --git a/lab_2/10_runtime_plot.png b/lab_2/10_runtime_plot.png new file mode 100644 index 0000000..0d1da7c Binary files /dev/null and b/lab_2/10_runtime_plot.png differ