Start latency measuring module

latency-measure/build/Makefile

+ARM_CC = arm-linux-gnueabihf-gcc
+ARM_PROG = main_arm
+PROG = main
+SRCDIR = ../src
+
+SRCS  = main.c
+SRCS += getip.c
+SRCS += send_packet.c
+
+OBJS = $(SRCS:%.c=%.o)
+
+CFLAGS = -Og -g -Wall -Werror -Wextra
+CFLAGS += -MD -MP
+CFLAGS += -I $(SRCDIR)
+CFLAGS += -std=gnu99
+
+LDFLAGS = -pthread
+
+vpath %.c $(SRCDIR)
+
+
+$(ARM_PROG): FORCE
+	make clean
+	make -e CC:=arm-linux-gnueabihf-gcc $(PROG)
+	mv $(PROG) $(ARM_PROG)
+
+FORCE:
+
+$(PROG): $(OBJS)
+	$(CC) $(LDFLAGS) $^ -o $@
+
+-include $(subst .c,.d,$(SRCS))
+
+run: $(PROG)
+	./$^
+
+clean:
+	$(RM) $(OBJS) $(PROG) $(subst .c,.d,$(SRCS))
+
+.PHONY: clean FORCE

latency-measure/src/main.c

+#include <errno.h>
+#include <error.h>
+#include <pthread.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "getip.h"
+#include "send_packet.h"
+
+#define CLOCK_ID CLOCK_MONOTONIC
+
+typedef struct thread_stat {
+  int nb_cycles;
+} thread_stat_t;
+
+typedef struct thread_param {
+  int interval;
+  int priority;
+  int max_cycles;
+  const char *ip_address;
+  thread_stat_t stats;
+} thread_param_t;
+
+
+// Real-time thread
+// Sends packets at a regular intervall
+static void *packet_sending_thread(void *p) {
+
+  struct timespec next;
+  struct sched_param priority;
+
+  thread_param_t *param = (thread_param_t *)p;
+
+  priority.sched_priority = param->priority;
+
+  int err = sched_setscheduler(0, SCHED_FIFO, &priority);
+
+  if (err)
+    error(EXIT_FAILURE, errno, "Couldn't set priority");
+
+  for(param->stats.nb_cycles = 0;; param->stats.nb_cycles++) {
+
+    if(param->max_cycles)
+      if(param->stats.nb_cycles >= param->max_cycles)
+        break;
+
+    clock_gettime(CLOCK_ID, &next);
+    next.tv_sec += param->interval;
+
+    send_udp_packet(param->ip_address);
+
+    clock_nanosleep(CLOCK_ID, TIMER_ABSTIME, &next, NULL);
+
+  }
+
+  return NULL;
+}
+
+static void process_options(int argc, char *argv[], thread_param_t * param) {
+
+  for(;;) {
+
+    int c = getopt(argc, argv, "l:p:i:");
+
+    if(c == -1)
+      break;
+
+    switch(c) {
+    case 'p':
+      param->priority = atoi(optarg);
+      break;
+    case 'l':
+      param->max_cycles = atoi(optarg);
+      break;
+    case 'i':
+      param->interval = atoi(optarg);
+      break;
+    default:
+      exit(EXIT_FAILURE);
+      break;
+    }
+  }
+
+  if (argc != optind + 1) {
+    printf("Usage: %s server_ip\n", argv[0]);
+    exit(EXIT_FAILURE);
+  }
+  param->ip_address = argv[optind];
+}
+
+// Main thread, has non-real time priority
+// Handles the IO and creates real time threads
+int main(int argc, char *argv[]) {
+
+  pthread_t thread;
+  thread_param_t param;
+
+  // Default values
+  param.interval = 1;
+  param.max_cycles = -1;
+  param.priority = 80;
+
+  process_options(argc, argv, &param);
+
+
+  int err =
+      pthread_create(&thread, NULL, packet_sending_thread, (void *)&param);
+
+  if(err)
+    error(EXIT_FAILURE, errno, "Couldn't create thread");
+
+  for (;;) {
+    usleep(100000);
+
+    printf("Nb cycles: %d\n", param.stats.nb_cycles);
+
+    if( param.max_cycles == param.stats.nb_cycles )
+      break;
+  }
+
+  exit(EXIT_SUCCESS);
+}