From 2ca61c07de772d95a8d89c9b3ba0bb62742830f7 Mon Sep 17 00:00:00 2001
From: Andrew <andreasohaodha@proton.me>
Date: Wed, 19 Mar 2025 07:03:08 +0000
Subject: [PATCH] [CT420]: Merge bm1.c & bm2.c

---
 .../assignments/assignment2/code/merged.c     | 168 ++++++++++++++++++
 1 file changed, 168 insertions(+)
 create mode 100644 year4/semester2/CT420/assignments/assignment2/code/merged.c

diff --git a/year4/semester2/CT420/assignments/assignment2/code/merged.c b/year4/semester2/CT420/assignments/assignment2/code/merged.c
new file mode 100644
index 00000000..6b0686e4
--- /dev/null
+++ b/year4/semester2/CT420/assignments/assignment2/code/merged.c
@@ -0,0 +1,168 @@
+// Compile code with gcc -o bm1 bm1.c -lrt -Wall -O2
+// Execute code with sudo ./bm1
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <sched.h>
+#include <errno.h>
+#include <string.h>
+#include <limits.h>
+
+#define ITERATIONS 1000
+#define NS_PER_SEC 1000000000L
+
+timer_t timer_id;
+volatile sig_atomic_t timer_expired = 0;
+volatile sig_atomic_t signal_received = 0;
+struct timespec start, end, sleep_time;
+
+void signal_handler(int signum) {
+    signal_received = 1;
+	clock_gettime(CLOCK_MONOTONIC, &end);
+}
+
+void timer_handler(int signum) {
+    timer_expired = 1;
+    clock_gettime(CLOCK_MONOTONIC, &end);
+}
+
+void configure_realtime_scheduling() {
+    struct sched_param param;
+    param.sched_priority = sched_get_priority_max(SCHED_FIFO);
+    if (sched_setscheduler(0, SCHED_FIFO, &param) == -1) {
+        perror("sched_setscheduler");
+        exit(EXIT_FAILURE);
+    }
+}
+
+void lock_memory() {
+    if (mlockall(MCL_CURRENT | MCL_FUTURE) == -1) {
+        perror("mlockall");
+        exit(EXIT_FAILURE);
+    }
+}
+
+void benchmark_nanosleep() {
+    // struct timespec start, end, sleep_time;
+    long long total_jitter = 0;
+    long long max_jitter = 0;
+    long long min_jitter = LLONG_MAX;
+
+    sleep_time.tv_sec = 0;
+    sleep_time.tv_nsec = 1000000; // 1 ms
+
+    for (int i = 0; i < ITERATIONS; i++) {
+        clock_gettime(CLOCK_MONOTONIC, &start);
+        nanosleep(&sleep_time, NULL);
+        clock_gettime(CLOCK_MONOTONIC, &end);
+
+        long long elapsed = (end.tv_sec - start.tv_sec) * NS_PER_SEC + (end.tv_nsec - start.tv_nsec);
+        long long jitter = elapsed - sleep_time.tv_nsec;
+
+        total_jitter += llabs(jitter);
+        if (jitter > max_jitter) max_jitter = jitter;
+        if (jitter < min_jitter) min_jitter = jitter;
+    }
+
+    printf("Nanosleep Benchmark:\n");
+    printf("Average jitter: %lld ns\n", total_jitter / ITERATIONS);
+    printf("Max jitter: %lld ns\n", max_jitter);
+    printf("Min jitter: %lld ns\n", min_jitter);
+}
+
+void benchmark_signal_latency() {
+    long long total_latency = 0;
+    long long max_latency = 0;
+    long long min_latency = LLONG_MAX;
+
+    signal(SIGUSR1, signal_handler);
+
+    for (int i = 0; i < ITERATIONS; i++) {
+        clock_gettime(CLOCK_MONOTONIC, &start);
+        kill(getpid(), SIGUSR1);
+        while (!signal_received);
+
+        long long latency = (end.tv_sec - start.tv_sec) * NS_PER_SEC + (end.tv_nsec - start.tv_nsec);
+        total_latency += latency;
+        if (latency > max_latency) max_latency = latency;
+        if (latency < min_latency) min_latency = latency;
+
+        signal_received = 0;
+    }
+
+    printf("\nSignal Latency Benchmark:\n");
+    printf("Average latency: %lld ns\n", total_latency / ITERATIONS);
+    printf("Max latency: %lld ns\n", max_latency);
+    printf("Min latency: %lld ns\n", min_latency);
+}
+
+void benchmark_timer() {
+    long long total_jitter = 0;
+    long long max_jitter = 0;
+    long long min_jitter = LLONG_MAX;
+
+    struct sigevent sev;
+    sev.sigev_notify = SIGEV_SIGNAL;
+    sev.sigev_signo = SIGRTMIN;
+    sev.sigev_value.sival_ptr = &timer_id;
+
+    if (timer_create(CLOCK_MONOTONIC, &sev, &timer_id) == -1) {
+        perror("timer_create");
+        exit(EXIT_FAILURE);
+    }
+
+    struct itimerspec its;
+    its.it_value.tv_sec = 0;
+    its.it_value.tv_nsec = 1000000; // 1 ms
+    its.it_interval = its.it_value;
+
+    signal(SIGRTMIN, timer_handler);
+
+    if (timer_settime(timer_id, 0, &its, NULL) == -1) {
+        perror("timer_settime");
+        exit(EXIT_FAILURE);
+    }
+    clock_gettime(CLOCK_MONOTONIC, &start);
+    for (int i = 0; i < ITERATIONS; i++) {
+        // while (!timer_expired);
+
+        while (!timer_expired) {
+            struct timespec ts = {0, 100};
+            nanosleep(&ts, NULL);
+        }
+
+        clock_gettime(CLOCK_MONOTONIC, &end);
+
+        long long elapsed = (end.tv_sec - start.tv_sec) * NS_PER_SEC + (end.tv_nsec - start.tv_nsec);
+        long long jitter = elapsed - its.it_interval.tv_nsec;
+
+        total_jitter += llabs(jitter);
+        if (jitter > max_jitter) max_jitter = jitter;
+        if (jitter < min_jitter) min_jitter = jitter;
+
+        timer_expired = 0;
+        start = end;
+    }
+
+    printf("\nTimer Benchmark:\n");
+    printf("Average jitter: %lld ns\n", total_jitter / ITERATIONS);
+    printf("Max jitter: %lld ns\n", max_jitter);
+    printf("Min jitter: %lld ns\n", min_jitter);
+
+    timer_delete(timer_id);
+}
+
+int main() {
+    configure_realtime_scheduling();
+    lock_memory();
+
+    benchmark_nanosleep();
+    benchmark_signal_latency();
+    benchmark_timer();
+
+    return 0;
+}