The "Holy Bible" for embedded engineers
Analyzing runtime behavior, memory usage, and performance characteristics through dynamic analysis tools and techniques in embedded software
Dynamic analysis examines program behavior during execution, providing insights into runtime performance, memory usage, and actual system behavior. Unlike static analysis, dynamic analysis runs the code and monitors its execution, making it essential for identifying issues that only manifest at runtime in embedded systems.
┌─────────────────────────────────────────────────────────────┐
│ Dynamic Analysis Categories │
├─────────────────────────────────────────────────────────────┤
│ Memory Analysis │ Memory leaks, overflows, corruption │
│ Performance Profiling│ CPU usage, timing, bottlenecks │
│ Thread Analysis │ Task scheduling, synchronization │
│ I/O Profiling │ File, network, and device I/O │
│ Exception Handling │ Error conditions and recovery │
│ Resource Monitoring │ CPU, memory, and peripheral usage │
└─────────────────────────────────────────────────────────────┘
Dynamic memory analysis tracks memory allocation and deallocation patterns:
// Example: Memory leak detection
void process_data_loop(void) {
uint8_t *buffer;
for (int i = 0; i < 1000; i++) {
buffer = malloc(1024); // Allocate memory
if (buffer != NULL) {
process_buffer(buffer);
// Memory leak: buffer is never freed
}
}
}
Performance profiling measures execution time and resource usage:
// Example: Function timing measurement
void measure_function_performance(void) {
uint32_t start_time = get_system_time();
// Function to measure
process_sensor_data();
uint32_t end_time = get_system_time();
uint32_t execution_time = end_time - start_time;
// Record performance data
record_performance_metric("process_sensor_data", execution_time);
}
Real-time analysis examines timing characteristics and interrupt behavior:
// Example: Interrupt latency measurement
volatile uint32_t interrupt_entry_time = 0;
volatile uint32_t interrupt_latency = 0;
void IRQ_Handler(void) {
uint32_t current_time = get_high_resolution_time();
if (interrupt_entry_time != 0) {
interrupt_latency = current_time - interrupt_entry_time;
update_latency_statistics(interrupt_latency);
}
interrupt_entry_time = current_time;
// Process interrupt
handle_interrupt();
}
// Dynamic analysis configuration
typedef struct {
bool memory_tracking_enabled;
bool performance_profiling_enabled;
bool thread_analysis_enabled;
uint32_t sampling_interval_ms;
uint32_t max_records;
} dynamic_analysis_config_t;
// Memory tracking structure
typedef struct {
void *address;
size_t size;
uint32_t allocation_time;
const char *function_name;
uint32_t line_number;
bool is_freed;
} memory_allocation_t;
// Performance metric structure
typedef struct {
const char *function_name;
uint32_t call_count;
uint32_t total_time;
uint32_t min_time;
uint32_t max_time;
uint32_t last_call_time;
} performance_metric_t;
#define MAX_MEMORY_RECORDS 1000
#define MAX_PERFORMANCE_RECORDS 100
memory_allocation_t memory_records[MAX_MEMORY_RECORDS];
performance_metric_t performance_records[MAX_PERFORMANCE_RECORDS];
uint32_t memory_record_count = 0;
uint32_t performance_record_count = 0;
// Track memory allocation
void* track_malloc(size_t size, const char *function, uint32_t line) {
void *ptr = malloc(size);
if (ptr != NULL && memory_record_count < MAX_MEMORY_RECORDS) {
memory_records[memory_record_count].address = ptr;
memory_records[memory_record_count].size = size;
memory_records[memory_record_count].allocation_time = get_system_time();
memory_records[memory_record_count].function_name = function;
memory_records[memory_record_count].line_number = line;
memory_records[memory_record_count].is_freed = false;
memory_record_count++;
}
return ptr;
}
// Track memory deallocation
void track_free(void *ptr) {
if (ptr != NULL) {
// Find and mark the allocation record
for (uint32_t i = 0; i < memory_record_count; i++) {
if (memory_records[i].address == ptr && !memory_records[i].is_freed) {
memory_records[i].is_freed = true;
break;
}
}
}
free(ptr);
}
// Detect memory leaks
void detect_memory_leaks(void) {
printf("=== Memory Leak Detection ===\n");
uint32_t leak_count = 0;
size_t total_leaked_bytes = 0;
for (uint32_t i = 0; i < memory_record_count; i++) {
if (!memory_records[i].is_freed) {
leak_count++;
total_leaked_bytes += memory_records[i].size;
printf("Leak %u: %p (%zu bytes) allocated in %s:%u\n",
leak_count,
memory_records[i].address,
memory_records[i].size,
memory_records[i].function_name,
memory_records[i].line_number);
}
}
printf("Total leaks: %u, Total leaked bytes: %zu\n",
leak_count, total_leaked_bytes);
}
// Start performance measurement
uint32_t start_performance_measurement(const char *function_name) {
uint32_t start_time = get_system_time();
// Find or create performance record
uint32_t record_index = find_or_create_performance_record(function_name);
if (record_index != UINT32_MAX) {
performance_records[record_index].last_call_time = start_time;
}
return start_time;
}
// End performance measurement
void end_performance_measurement(const char *function_name, uint32_t start_time) {
uint32_t end_time = get_system_time();
uint32_t execution_time = end_time - start_time;
uint32_t record_index = find_performance_record(function_name);
if (record_index != UINT32_MAX) {
performance_records[record_index].call_count++;
performance_records[record_index].total_time += execution_time;
if (execution_time < performance_records[record_index].min_time ||
performance_records[record_index].min_time == 0) {
performance_records[record_index].min_time = execution_time;
}
if (execution_time > performance_records[record_index].max_time) {
performance_records[record_index].max_time = execution_time;
}
}
}
// Generate performance report
void generate_performance_report(void) {
printf("=== Performance Profiling Report ===\n");
for (uint32_t i = 0; i < performance_record_count; i++) {
if (performance_records[i].call_count > 0) {
float avg_time = (float)performance_records[i].total_time /
performance_records[i].call_count;
printf("%s:\n", performance_records[i].function_name);
printf(" Calls: %u\n", performance_records[i].call_count);
printf(" Total Time: %u ms\n", performance_records[i].total_time);
printf(" Average Time: %.2f ms\n", avg_time);
printf(" Min Time: %u ms\n", performance_records[i].min_time);
printf(" Max Time: %u ms\n", performance_records[i].max_time);
printf("\n");
}
}
}
// Real-time performance monitoring structure
typedef struct {
uint32_t cpu_usage;
uint32_t memory_usage;
uint32_t interrupt_count;
uint32_t task_switch_count;
uint32_t timestamp;
} real_time_metrics_t;
#define MAX_METRICS_HISTORY 1000
real_time_metrics_t metrics_history[MAX_METRICS_HISTORY];
uint32_t metrics_index = 0;
// Collect real-time metrics
void collect_real_time_metrics(void) {
real_time_metrics_t current_metrics;
current_metrics.cpu_usage = get_cpu_usage_percentage();
current_metrics.memory_usage = get_memory_usage_bytes();
current_metrics.interrupt_count = get_interrupt_count();
current_metrics.task_switch_count = get_task_switch_count();
current_metrics.timestamp = get_system_time();
// Store in circular buffer
metrics_history[metrics_index] = current_metrics;
metrics_index = (metrics_index + 1) % MAX_METRICS_HISTORY;
}
// Analyze real-time performance trends
void analyze_performance_trends(void) {
printf("=== Performance Trend Analysis ===\n");
uint32_t total_cpu = 0;
uint32_t total_memory = 0;
uint32_t total_interrupts = 0;
uint32_t sample_count = 0;
for (uint32_t i = 0; i < MAX_METRICS_HISTORY; i++) {
if (metrics_history[i].timestamp != 0) {
total_cpu += metrics_history[i].cpu_usage;
total_memory += metrics_history[i].memory_usage;
total_interrupts += metrics_history[i].interrupt_count;
sample_count++;
}
}
if (sample_count > 0) {
printf("Average CPU Usage: %.1f%%\n", (float)total_cpu / sample_count);
printf("Average Memory Usage: %u bytes\n", total_memory / sample_count);
printf("Average Interrupt Rate: %.1f/sec\n",
(float)total_interrupts / sample_count);
}
}
// Memory fragmentation analysis
typedef struct {
size_t total_allocated;
size_t total_freed;
size_t peak_usage;
uint32_t allocation_count;
uint32_t deallocation_count;
size_t largest_free_block;
uint32_t fragmentation_score;
} memory_fragmentation_t;
// Analyze memory fragmentation
void analyze_memory_fragmentation(void) {
memory_fragmentation_t frag_analysis = {0};
// Calculate fragmentation metrics
for (uint32_t i = 0; i < memory_record_count; i++) {
if (memory_records[i].is_freed) {
frag_analysis.total_freed += memory_records[i].size;
frag_analysis.deallocation_count++;
} else {
frag_analysis.total_allocated += memory_records[i].size;
frag_analysis.allocation_count++;
}
}
// Calculate peak usage
frag_analysis.peak_usage = frag_analysis.total_allocated;
// Calculate fragmentation score (0-100, higher = more fragmented)
if (frag_analysis.peak_usage > 0) {
frag_analysis.fragmentation_score =
(uint32_t)((frag_analysis.total_freed * 100) / frag_analysis.peak_usage);
}
printf("=== Memory Fragmentation Analysis ===\n");
printf("Total Allocated: %zu bytes\n", frag_analysis.total_allocated);
printf("Total Freed: %zu bytes\n", frag_analysis.total_freed);
printf("Peak Usage: %zu bytes\n", frag_analysis.peak_usage);
printf("Fragmentation Score: %u%%\n", frag_analysis.fragmentation_score);
}
// Interrupt analysis structure
typedef struct {
uint32_t irq_number;
uint32_t call_count;
uint32_t total_execution_time;
uint32_t min_execution_time;
uint32_t max_execution_time;
uint32_t last_execution_time;
} interrupt_analysis_t;
// Task analysis structure
typedef struct {
const char *task_name;
uint32_t priority;
uint32_t execution_count;
uint32_t total_execution_time;
uint32_t max_execution_time;
uint32_t missed_deadlines;
} task_analysis_t;
// Track interrupt execution
void track_interrupt_execution(uint32_t irq_number, uint32_t execution_time) {
// Find or create interrupt record
uint32_t record_index = find_or_create_interrupt_record(irq_number);
if (record_index != UINT32_MAX) {
interrupt_analysis_t *record = &interrupt_records[record_index];
record->call_count++;
record->total_execution_time += execution_time;
record->last_execution_time = execution_time;
if (execution_time < record->min_execution_time ||
record->min_execution_time == 0) {
record->min_execution_time = execution_time;
}
if (execution_time > record->max_execution_time) {
record->max_execution_time = execution_time;
}
}
}
Q: What is the difference between static and dynamic analysis? A: Static analysis examines code without execution, while dynamic analysis runs the code and monitors its runtime behavior. Dynamic analysis can detect issues like memory leaks, performance bottlenecks, and runtime errors that static analysis might miss.
Q: What are the main challenges of dynamic analysis in embedded systems? A: Performance overhead, limited memory for analysis data, real-time constraints, platform-specific tool limitations, and the need to minimize interference with system operation while collecting meaningful data.
Q: How would you implement memory leak detection in an embedded system? A: Track all memory allocations and deallocations, maintain a list of allocated blocks with metadata, periodically scan for unreleased memory, use efficient data structures to minimize overhead, and implement circular buffers for historical data.
Q: How do you handle the performance overhead of dynamic analysis? A: Use sampling instead of continuous monitoring, implement efficient data structures, limit the scope of analysis, use hardware features when available, and run comprehensive analysis only when needed.
Q: How would you design a real-time performance monitoring system for a multi-core embedded system? A: Use shared memory regions for data collection, implement atomic operations for thread safety, use hardware performance counters, implement non-blocking data collection, and use inter-core communication for coordinated analysis.
Q: How do you ensure dynamic analysis doesn’t interfere with system reliability? A: Implement analysis as a separate, isolated module, use hardware features when available, implement fail-safe mechanisms, thoroughly test the analysis system, and design it to gracefully degrade when resources are limited.
Next Steps: Explore Code Coverage for testing completeness assessment or Static Analysis for code quality analysis.