Modern Technology Practices

It's a repo to store everything related to this course.

01- Input output flush

Description

We test all scenarios for flush function in C language.
We can see in the outputs files different cases and different outputs.

How to Run the Program

The program accepts several parameters to enable or disable specific options:

• -d: Default scenario - Uses fflush to ensure immediate output for both STDOUT and STDERR.
• -n: Newline scenario - Adds \n to the output, utilizing line-buffering for STDOUT and immediate output for STDERR.
• -s: Without fflush - Omits fflush, so STDOUT may delay until the program exits, while STDERR appears immediately.
• -r: Redirect output - Demonstrates behavior when output is redirected to a file without \n or fflush, causing potential delay in STDOUT while STDERR appears immediately.

Example Commands

To compile and run each scenario, execute the following commands:

# Compile the program
gcc -o program main.c

# Run default scenario with fflush
./program -d

# Run scenario with newline (\n) addition
./program -n

# Run scenario without fflush
./program -s

# Run scenario with redirected output
./program -r

# Run all scenarios with the script
./run_experiments.sh

Comperison between cases

• Original program:
  Here we used the the original code, and we can see that "STDOUT" and "STDERR" appear immediately due to explicit fflush.
• With \n added:
  We see that both "STDOUT\n" and "STDERR\n" appear immediately due to line-buffering.
• Without fflush:
  "STDOUT" delay and wait until the program ends, "STDERR" appears immediately.
• Redirecting output to a file without "/n" or flush:
  "STDOUT" may delay, "STDERR" apears immediately.

02- Overcommit

Description

This program demonstrates how memory allocation, reading, and writing operations impact system behavior. By simulating controlled memory access patterns, the program explores scenarios of paging, memory consumption, and system performance under varying conditions.

The program is parameterized to allow flexible configuration of memory size, access modes, pause frequency, and duration. It also enables monitoring of system behavior using external tools like free.

How to use

• Compilation

gcc main.c

Usage

• You can check all configurations using:

./a.out -h

• Or use the following table:

Option	Description	Default value
-m, --memory_size	Memory size to allocate (MB)	128
-a, --access_mode	Access mode: read or write	read
-p, --pause_steps	Number of steps (4 KB blocks) befure pausing	1000
-d, --pause_time	Pause duration in milliseconds	100
-h, --help	Show help message and exit

Examples

1. Default

./a.out

2. Write mode

./a.out -m 256 -a write -p 500 -d 50

3. Stress test

./a.out -m 5120 -a write -p 10000 -d 0

3. Small allocaton with fast pauses

./a.out -m 500 -a read -p 100 -d 10

3. Help Message

./a.out -h

Monitoring

Using free -m during the pauses to observe total system memory usage in MB.

Results

1. Read vs Write
   • Read Mode : Memory usage remains stable.
   • Write Mode : Physical memory allocation grows as pages are dirtied. When exceeding the maximum system will crash.
2. Continuous Write with no pauses:
   • Causes rapid memory consumption and high system load.

03- Fractal

Description

This module demonstrates generating fractals in C and saving the results in PGM format. I applied three fractals as I found:

• Julia
• Sierpinski Carpet
• Mandelbrot Set

I reused image.c to manage the image buffers and write the result to .pgm

How To Use

1. The main entry point is main.c that contains the fractal generation codes.

2. Compilation:

   • Option A: Using a Makefile (recommended)

     make
     make clean

     After make, you should have two executables:

     1. fractal (production)
     2. test_fractal (test binary)

   • Option B: Manual Commands
     Production build:

     gcc -c image.c -o image.o
     gcc -c fractal.c -o fractal.o -lm
     gcc -c main.c -o main.o -lm
     gcc image.o fractal.o main.o -o fractal -lm

     Test build:

     gcc -c image.c -o image.o
     gcc -c fractal.c -o fractal.o -lm
     gcc -c test_fractal.c -o test_fractal.o
     gcc image.o fractal.o test_fractal.o -o test_fractal -lm

3. Running: We can pass two params:

• Fractal type: julia, sierpinski or mandelbrot.
• Output filename default fractal_output.pgm

./fractal
./fractal sierpinski carpet.pgm
./fractal mandelbrot mandelbrot.pgm

4. Viewing PGM:

convert fractal_output.pgm fractal_output.png