Calculating averaged RTT values at sender.

Distinguish between delay and app layer latency in evaluation scripts.

eval.py

@@ -13,7 +13,7 @@ if __name__ == "__main__":
 
     # TODO: support multiple tests via proper socket termination
     setups = [
-        perf.TestSetup(packets=2**10,delay=0,loss=0.5,reorder=0,duplicate=0)
+        perf.TestSetup(packets=2**10,delay=0,loss=0,reorder=0,duplicate=0)
     ]
 
     for setup in setups:

src/defines.h

@@ -14,6 +14,8 @@
 #define N_START 7
 #define N_P_START 1
 
+#define RRT_ALPHA 0.125
+
 // Uncomment the line below if you are compiling on Windows.
 // #define WINDOWS
 #include <stdio.h>

src/prrt/socket.c

@@ -26,6 +26,9 @@ PrrtSocket* PrrtSocket_create(const uint16_t port, const uint8_t is_sender) {
     sock_ptr->sequenceNumberSource = 1;
     sock_ptr->sequenceNumberRedundancy = 1;
 
+    sock_ptr->rttMean = 0;
+    sock_ptr->rttDev = 0;
+
     sock_ptr->dataStore = NULL;
 
     check(sock_ptr->dataSocketFd = socket(AF_INET, SOCK_DGRAM, 0), "Cannot create data socket.")
@@ -253,7 +256,7 @@ int PrrtSocket_close(PrrtSocket *sock_ptr) {
         return -1;
 }
 
-PrrtPacket *PrrtSocket_recv_feedback(const PrrtSocket *sock_ptr, const size_t length)
+PrrtPacket *PrrtSocket_recv_feedback(PrrtSocket *sock_ptr, const size_t length)
 {
     char bufin[MAX_PAYLOAD_LENGTH];
     ssize_t n;
@@ -280,8 +283,10 @@ PrrtPacket *PrrtSocket_recv_feedback(const PrrtSocket *sock_ptr, const size_t le
     PrrtPacket_decode(bufin, (uint16_t) n, packet_ptr);
 
     PrrtPacketFeedbackPayload* feedbackPayload = packet_ptr->payload;
-    printf("FTT Timestamp: %d\n", feedbackPayload->forward_trip_timestamp);
-    printf("RTT: %d\n", receive_time - feedbackPayload->forward_trip_timestamp);
+    int32_t delta = (receive_time - feedbackPayload->forward_trip_timestamp) - sock_ptr->rttMean;
+    // TODO: ensure that there are no arithemtic problems via rounding etc.
+    sock_ptr->rttMean = (uint32_t) (sock_ptr->rttMean + RRT_ALPHA * delta);
+    sock_ptr->rttDev = (uint32_t) (sock_ptr->rttDev + RRT_ALPHA * (labs(delta) - sock_ptr->rttDev));
 
     return packet_ptr;
 

src/prrt/socket.h

@@ -43,6 +43,9 @@ typedef struct prrtSocket {
 
     uint32_t lastSentTimestamp;
     uint32_t lastReceivedTimestamp;
+
+    uint32_t rttMean;
+    uint32_t rttDev;
 } PrrtSocket;
 
 
@@ -52,6 +55,6 @@ int PrrtSocket_close(PrrtSocket *sock_ptr);
 int PrrtSocket_connect(PrrtSocket *sock_ptr, const char *host, const uint16_t port);
 int PrrtSocket_send(PrrtSocket *sock_ptr, const uint8_t *data, const size_t data_len);
 int32_t PrrtSocket_recv(PrrtSocket *sock_ptr, void *buf_ptr);
-PrrtPacket *PrrtSocket_recv_feedback(const PrrtSocket *sock_ptr, const size_t length);
+PrrtPacket *PrrtSocket_recv_feedback(PrrtSocket *sock_ptr, const size_t length);
 
 #endif // PRRT_SOCKET_H

tests/perf/__init__.py

@@ -72,7 +72,7 @@ class TestResults(object):
         delayStd = np.std(delayValues) * 1000
         delayMin = np.min(delayValues) * 1000
         delayMax = np.max(delayValues) * 1000
-        delays = "Delay Profile [ms]: %f+-%f [%f - %f]" % (delayMean, delayStd, delayMin, delayMax)
+        delays = "Application Latency [ms]: %f+-%f [%f - %f]" % (delayMean, delayStd, delayMin, delayMax)
         return "%s\n%s\n%s" % (loss, duplicates, delays)
 
 class TestSetup(object):