Add option to print histograms to stdout on exit

packet-exchange/src/send_packet.c

@@ -41,7 +41,7 @@
 
 #define MESSAGE ((uint32_t)0x00FACADE)
 
-static void process_timestamps(struct packet_timestamps *packet_ts);
+static void process_timestamps(struct packet_timestamps *packet_ts, int64_t histograms[NB_HISTOGRAMS][MAX_HIST_VAL]);
 static void init_tx_buffer(size_t _tx_buffer_len);
 
 static int so_priority = 3;
@@ -148,7 +148,8 @@ uint64_t get_txtime() {
  */
 struct packet_timestamps send_udp_packet(int use_etf, int use_timestamps,
                                          uint64_t txtime,
-                                         const char *server_ip) {
+                                         const char *server_ip,
+                                         int64_t histograms[NB_HISTOGRAMS][MAX_HIST_VAL]) {
   char control[CMSG_SPACE(sizeof(txtime))] = {};
   struct sockaddr_in sin;
   struct cmsghdr *cmsg;
@@ -205,7 +206,7 @@ struct packet_timestamps send_udp_packet(int use_etf, int use_timestamps,
   if (use_timestamps) {
     res = poll(&poll_fd, 1, 0);
     if (res > 0)
-      process_timestamps(&packet_ts);
+      process_timestamps(&packet_ts, histograms);
     else
       fprintf(stderr, "select failed\n");
   }
@@ -213,7 +214,27 @@ struct packet_timestamps send_udp_packet(int use_etf, int use_timestamps,
   return packet_ts;
 }
 
-static void process_timestamps(struct packet_timestamps *packet_ts) {
+static void fill_histograms(struct packet_timestamps *packet_ts, int64_t histograms[NB_HISTOGRAMS][MAX_HIST_VAL]) {
+  uint64_t user_space_time = packet_ts->user_call_sendmsg - packet_ts->user_enter_send;
+  uint64_t kernel_space_time = packet_ts->kernel_leave - packet_ts->user_call_sendmsg;
+
+  user_space_time /= 1000u;
+  kernel_space_time /= 1000u;
+
+  if(user_space_time > MAX_HIST_VAL) {
+    fprintf(stderr, "user_space_time value too high: %" PRIu64 "us\n", user_space_time);
+    exit(EXIT_FAILURE);
+  }
+  if(kernel_space_time > MAX_HIST_VAL) {
+    fprintf(stderr, "kernel_space_time value too high: %" PRIu64 "us\n", kernel_space_time);
+    exit(EXIT_FAILURE);
+  }
+
+  histograms[0][user_space_time]++;
+  histograms[1][kernel_space_time]++;
+}
+
+static void process_timestamps(struct packet_timestamps *packet_ts, int64_t histograms[NB_HISTOGRAMS][MAX_HIST_VAL]) {
   char data[256];
   struct msghdr msg;
   struct iovec entry;
@@ -243,6 +264,7 @@ static void process_timestamps(struct packet_timestamps *packet_ts) {
     if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SO_TIMESTAMPING) {
       struct timespec *stamp = (struct timespec *)CMSG_DATA(cmsg);
       packet_ts->kernel_leave = ts_to_uint(*stamp);
+      fill_histograms(packet_ts, histograms);
     } else {
 #ifdef DEBUG
       fprintf(stderr, "process_timestamps: level %d type %d", cmsg->cmsg_level,

packet-exchange/src/send_packet.h

@@ -4,6 +4,8 @@
 #include <stdint.h>
 #include <stdio.h>
 
+#include "utilities.h"
+
 struct packet_timestamps {
   uint64_t user_enter_send;
   uint64_t user_call_sendmsg;
@@ -11,6 +13,6 @@ struct packet_timestamps {
 };
 
 void init_udp_send(int use_etf, int use_timestamps, int so_priority, char * network_if, size_t tx_buffer_len);
-struct packet_timestamps send_udp_packet(int use_etf, int use_timestamps, uint64_t txtime, const char *server_ip);
+struct packet_timestamps send_udp_packet(int use_etf, int use_timestamps, uint64_t txtime, const char *server_ip, int64_t histograms[NB_HISTOGRAMS][MAX_HIST_VAL]);
 
 #endif

packet-exchange/src/server.c

@@ -98,7 +98,7 @@ static void *packet_receiving_thread(void *p) {
   for (stats->packets_received = 0;; stats->packets_received++) {
     if (param->tsn_task == RTT_TASK) {
       recv_udp_packet(param->sockfd);
-      send_udp_packet(0, 0, 0, param->ip_address);
+      send_udp_packet(0, 0, 0, param->ip_address, NULL);
     } else if (param->tsn_task == RECV_PACKET_TASK) {
       recv_udp_packet(param->sockfd);
 

packet-exchange/src/utilities.h

@@ -10,6 +10,8 @@
 #define NSEC_PER_SEC UINT64_C(1000000000)
 #define SERVER_PORT "50000"
 #define SERVER_PORT_INT 50000
+#define MAX_HIST_VAL 1000
+#define NB_HISTOGRAMS 3
 
 uint64_t ts_to_uint(struct timespec t);
 void add_ns(struct timespec *t, uint64_t ns);