Exercise on memory management analyzer

exercises/mem_analyzer/Makefile

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+CC = gcc
+CFLAGS = -Wall -Wextra -Wpadded -g -fsanitize=address
+TARGET = mem_analyzer
+SRC = mem_utils.c main.c
+OBJ = $(SRC:.c=.o)
+
+.PHONY: all build run test valgrind clean
+
+all: build
+
+build: $(TARGET)
+
+$(TARGET): $(OBJ)
+	$(CC) $(CFLAGS) -o $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+run: build
+	./$(TARGET)
+
+test: build
+	./$(TARGET) test
+
+valgrind: build
+	valgrind --leak-check=full --show-leak-kinds=all ./$(TARGET)
+
+clean:
+	rm -f $(TARGET) $(OBJ)

exercises/mem_analyzer/README.md

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+# 🧠 Memory Management Analyzer
+
+This project demonstrates how different memory allocation methods (`malloc`, `calloc`, and `mmap`) perform in terms of speed and memory usage in a simulated workload.
+
+---
+
+## 📜 Description
+The program dynamically allocates and frees memory blocks of varying sizes, measuring:
+
+- Allocation and deallocation times.
+- Memory usage via `/proc/self/status` or `/proc/self/statm`.
+- Peak memory consumption during execution.
+
+It produces a report comparing performance across allocation methods.
+
+---
+
+## 🚀 Features
+- **Dynamic Allocation Testing** – compares `malloc`, `calloc`, and `mmap`.
+- **Performance Metrics** – measures allocation/deallocation times.
+- **Memory Usage Tracking** – monitors real-time process memory usage.
+- **Optional Memory Leak Simulation** – detects unfreed memory using Valgrind.
+- **CLI Mode Selection** – choose allocator at runtime (`--malloc`, `--calloc`, `--mmap`).
+
+---
+
+## 🛠️ Build
+```bash
+make
+```
+
+---
+
+## ▶️ Run
+```bash
+./mem_analyzer --malloc
+./mem_analyzer --calloc
+./mem_analyzer --mmap
+```
+
+---
+
+## 🧪 Test & Debug
+```bash
+make valgrind
+```
+
+---
+
+## 📊 Example Output
+```
+Allocator: malloc
+Blocks: 10000
+Average Allocation Time: 0.24 μs
+Average Free Time: 0.18 μs
+Peak Memory Usage: 2.5 MB
+```
+
+---
+
+## 📂 Project Structure
+```
+mem_analyzer/
+ ├── README.md
+ ├── Makefile
+ └── main.c
+```
+
+---
+
+## 🔍 Learning Objectives
+- Understand differences between `malloc`, `calloc`, and `mmap`.
+- Learn to measure memory usage through `/proc`.
+- Practice debugging memory errors with Valgrind.
+- Gain insight into memory allocation strategies in Linux.
+
+---

exercises/mem_analyzer/main.c

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+#include "mem_utils.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <time.h>
+
+/* Run allocation benchmark using malloc */
+struct Stats *bench_malloc();
+
+/* Run allocation benchmark using calloc */
+struct Stats *bench_calloc();
+
+/* Run allocation benchmark using mmap */
+struct Stats *bench_mmap();
+
+typedef struct Stats *(*StatsFn)(void);
+
+/* Memory blocks size to allocate for testing */
+static size_t size_blocks[BLOCK_NUM] = {1024, 2048, 4096, 100000, 8192};
+
+int main(int argc, char const *argv[])
+{
+	const StatsFn benchmarks[] = {bench_malloc, bench_calloc, bench_mmap};
+	for (int i = 0; i < 3; i++) {
+		StatsFn benchmark = benchmarks[i];
+		struct Stats *result = benchmark();
+		print_stats(result);
+		free(result);
+		printf("-------------------------------------------\n");
+	}
+	return 0;
+}
+
+struct Stats *bench_malloc()
+{
+	// Benchmark malloc function
+	double peak_mem = 0.0;
+	double m_elapsed_times[BLOCK_NUM] = {0};
+	double f_elapsed_times[BLOCK_NUM] = {0};
+	for (int i = 0; i < BLOCK_NUM; i++) {
+		size_t size = size_blocks[i];
+		struct timespec m_start, f_start, m_end, f_end;
+
+		// malloc
+		clock_gettime(CLOCK_MONOTONIC, &m_start);
+		void *ptr = malloc(size);
+		clock_gettime(CLOCK_MONOTONIC, &m_end);
+		m_elapsed_times[i] = ((m_end.tv_sec - m_start.tv_sec) +
+				      (m_end.tv_nsec - m_start.tv_nsec)) /
+		    1e9;
+
+		double curr_mem_usage = get_mem_usage();
+		if (peak_mem <= curr_mem_usage) {
+			peak_mem = curr_mem_usage;
+		}
+
+		// free
+		clock_gettime(CLOCK_MONOTONIC, &f_start);
+		free(ptr);
+		clock_gettime(CLOCK_MONOTONIC, &f_end);
+		f_elapsed_times[i] = ((f_end.tv_sec - f_start.tv_sec) +
+				      (f_end.tv_nsec - f_start.tv_nsec)) /
+		    1e9;
+	}
+
+	struct Stats *stats = (struct Stats *)malloc(sizeof(struct Stats));
+	if (!stats) {
+		perror("malloc");
+		exit(1);
+	}
+	stats->allocator_type = "malloc";
+	stats->nr_allocations = BLOCK_NUM;
+	stats->avg_alloc_time = avg(m_elapsed_times, BLOCK_NUM);
+	stats->avg_free_time = avg(f_elapsed_times, BLOCK_NUM);
+	stats->mem_usage_mb = peak_mem;
+	return stats;
+}
+
+struct Stats *bench_calloc()
+{
+	// Benchmark malloc function
+	double peak_mem = 0.0;
+	double m_elapsed_times[BLOCK_NUM] = {0};
+	double f_elapsed_times[BLOCK_NUM] = {0};
+	for (int i = 0; i < BLOCK_NUM; i++) {
+		size_t size = size_blocks[i];
+		struct timespec m_start, f_start, m_end, f_end;
+
+		// malloc
+		clock_gettime(CLOCK_MONOTONIC, &m_start);
+		void *ptr = calloc(1, size);
+		clock_gettime(CLOCK_MONOTONIC, &m_end);
+		m_elapsed_times[i] = ((m_end.tv_sec - m_start.tv_sec) +
+				      (m_end.tv_nsec - m_start.tv_nsec)) /
+		    1e9;
+
+		double curr_mem_usage = get_mem_usage();
+		if (peak_mem <= curr_mem_usage) {
+			peak_mem = curr_mem_usage;
+		}
+
+		// free
+		clock_gettime(CLOCK_MONOTONIC, &f_start);
+		free(ptr);
+		clock_gettime(CLOCK_MONOTONIC, &f_end);
+		f_elapsed_times[i] = ((f_end.tv_sec - f_start.tv_sec) +
+				      (f_end.tv_nsec - f_start.tv_nsec)) /
+		    1e9;
+	}
+
+	struct Stats *stats = (struct Stats *)malloc(sizeof(struct Stats));
+	if (!stats) {
+		perror("malloc");
+		exit(1);
+	}
+	stats->allocator_type = "calloc";
+	stats->nr_allocations = BLOCK_NUM;
+	stats->avg_alloc_time = avg(m_elapsed_times, BLOCK_NUM);
+	stats->avg_free_time = avg(f_elapsed_times, BLOCK_NUM);
+	stats->mem_usage_mb = peak_mem;
+	return stats;
+}
+
+struct Stats *bench_mmap()
+{
+	// Benchmark malloc function
+	double peak_mem = 0.0;
+	double m_elapsed_times[BLOCK_NUM] = {0};
+	double f_elapsed_times[BLOCK_NUM] = {0};
+	for (int i = 0; i < BLOCK_NUM; i++) {
+		size_t size = size_blocks[i];
+		struct timespec m_start, f_start, m_end, f_end;
+
+		// malloc
+		clock_gettime(CLOCK_MONOTONIC, &m_start);
+		void *ptr = mmap(NULL, size, PROT_READ | PROT_WRITE,
+				 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+		clock_gettime(CLOCK_MONOTONIC, &m_end);
+		m_elapsed_times[i] = ((m_end.tv_sec - m_start.tv_sec) +
+				      (m_end.tv_nsec - m_start.tv_nsec)) /
+		    1e9;
+
+		double curr_mem_usage = get_mem_usage();
+		if (peak_mem <= curr_mem_usage) {
+			peak_mem = curr_mem_usage;
+		}
+
+		// free
+		clock_gettime(CLOCK_MONOTONIC, &f_start);
+		munmap(ptr, size);
+		clock_gettime(CLOCK_MONOTONIC, &f_end);
+		f_elapsed_times[i] = ((f_end.tv_sec - f_start.tv_sec) +
+				      (f_end.tv_nsec - f_start.tv_nsec)) /
+		    1e9;
+	}
+
+	struct Stats *stats = (struct Stats *)malloc(sizeof(struct Stats));
+	if (!stats) {
+		perror("malloc");
+		exit(1);
+	}
+	stats->allocator_type = "mmap";
+	stats->nr_allocations = BLOCK_NUM;
+	stats->avg_alloc_time = avg(m_elapsed_times, BLOCK_NUM);
+	stats->avg_free_time = avg(f_elapsed_times, BLOCK_NUM);
+	stats->mem_usage_mb = peak_mem;
+	return stats;
+}

exercises/mem_analyzer/mem_utils.c

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+#include "mem_utils.h"
+#include <stdio.h>
+#include <string.h>
+
+void print_stats(struct Stats *stats)
+{
+	printf("Allocator: %s\nBlocks: %ld\nAvarage Allocation Time: %.2f "
+	       "μs\nAvarage Free Time: %.2f μs\nPeak Memory Usage: %.2f MB\n",
+	       stats->allocator_type, stats->nr_allocations,
+	       stats->avg_alloc_time*1e6, stats->avg_free_time*1e6,
+	       stats->mem_usage_mb);
+}
+
+double avg(double *values, int size)
+{
+	double sum = 0.0;
+	for (int i = 0; i < size; i++) {
+		sum += *(values + i);
+	}
+	return size > 0 ? sum / size : 0.0;
+}
+
+double get_mem_usage()
+{
+	FILE *fp = fopen("/proc/self/status", "r");
+	if (!fp) {
+		perror("fopen");
+		return 1;
+	}
+
+  int found = 0;
+	char line[256];
+	while (fgets(line, sizeof(line), fp)) {
+		if (strncmp(line, "VmRSS:", 6) == 0) {
+      found = 1;
+			break;
+		}
+	}
+	fclose(fp);
+
+  if (!found) {
+    fprintf(stderr, "VmRSS not found in /proc/self/status\n");
+    return 0.0;
+  }
+
+	return strtod(line + 6, NULL) / 1024.0;
+}

exercises/mem_analyzer/mem_utils.h

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+#ifndef MEM_UTILS_H
+#define MEM_UTILS_H
+
+#include <stdlib.h>
+
+/* Block number under testing */
+#define BLOCK_NUM 5
+
+struct Stats {
+	const char *allocator_type;
+	size_t nr_allocations;
+	double avg_alloc_time;
+	double avg_free_time;
+	double mem_usage_mb;
+};
+
+/* Print on STDOUT the memory stats collected */
+void print_stats(struct Stats *);
+
+/* Calculate arithmetic average */
+double avg(double *, int size);
+
+/* Read in the a Linux system at /proc/self/status file the RSS field */
+double get_mem_usage();
+
+#endif