X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lttv%2Flttv%2Fsync%2Fevent_analysis_eval.c;h=b63fa54f91b49ab12fc761d4e906a9250103a33d;hb=4ee223e50270f894ec866b07c00ad49dff666173;hp=05a49acca39c9c1114245e53a9e2c6b6f87fd6cb;hpb=2bd4b3e43e525da7b4c9738915ec847f7fe4906a;p=lttv.git

diff --git a/lttv/lttv/sync/event_analysis_eval.c b/lttv/lttv/sync/event_analysis_eval.c
index 05a49acc..b63fa54f 100644
--- a/lttv/lttv/sync/event_analysis_eval.c
+++ b/lttv/lttv/sync/event_analysis_eval.c
@@ -17,6 +17,7 @@
  */
 
 #define _GNU_SOURCE
+#define _ISOC99_SOURCE
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
@@ -24,12 +25,14 @@
 
 #include <arpa/inet.h>
 #include <errno.h>
+#include <math.h>
 #include <netinet/in.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <unistd.h>
 
 #include "lookup3.h"
 #include "sync_chain.h"
@@ -49,6 +52,10 @@ static void analyzeBroadcastEval(SyncState* const syncState, Broadcast* const
 	broadcast);
 static GArray* finalizeAnalysisEval(SyncState* const syncState);
 static void printAnalysisStatsEval(SyncState* const syncState);
+static void writeAnalysisGraphsPlotsEval(FILE* stream, SyncState* const
+	syncState, const unsigned int i, const unsigned int j);
+static void writeAnalysisGraphsOptionsEval(FILE* stream, SyncState*
+    const syncState, const unsigned int i, const unsigned int j);
 
 // Functions specific to this module
 static void registerAnalysisEval() __attribute__((constructor (102)));
@@ -59,6 +66,22 @@ static void gdnDestroyDouble(gpointer data);
 static void readRttInfo(GHashTable* rttInfo, FILE* rttFile);
 static void positionStream(FILE* stream);
 
+static void gfSum(gpointer data, gpointer userData);
+static void gfSumSquares(gpointer data, gpointer userData);
+static void ghfPrintExchangeRtt(gpointer key, gpointer value, gpointer user_data);
+
+static void initGraphs(SyncState* const syncState);
+static void writeGraphFiles(SyncState* const syncState);
+static void dumpBinToFile(const uint32_t* const bin, const uint32_t total,
+	FILE* const file);
+static void destroyGraphs(SyncState* const syncState);
+static unsigned int binNum(const double value) __attribute__((pure));
+static double binStart(const unsigned int binNum) __attribute__((pure));
+static double binEnd(const unsigned int binNum) __attribute__((pure));
+
+
+const unsigned int binNb= 10000;
+double binBase;
 
 static AnalysisModule analysisModuleEval= {
 	.name= "eval",
@@ -69,15 +92,15 @@ static AnalysisModule analysisModuleEval= {
 	.analyzeBroadcast= &analyzeBroadcastEval,
 	.finalizeAnalysis= &finalizeAnalysisEval,
 	.printAnalysisStats= &printAnalysisStatsEval,
-	.writeAnalysisGraphsPlots= NULL,
-	.writeAnalysisGraphsOptions= NULL,
+	.writeAnalysisGraphsPlots= &writeAnalysisGraphsPlotsEval,
+	.writeAnalysisGraphsOptions= &writeAnalysisGraphsOptionsEval,
 };
 
 static ModuleOption optionEvalRttFile= {
 	.longName= "eval-rtt-file",
 	.hasArg= REQUIRED_ARG,
 	{.arg= NULL},
-	.optionHelp= "specify the file containing rtt information",
+	.optionHelp= "specify the file containing RTT information",
 	.argHelp= "FILE",
 };
 
@@ -133,17 +156,249 @@ static void initAnalysisEval(SyncState* const syncState)
 
 	if (syncState->stats)
 	{
-		analysisData->stats= malloc(sizeof(AnalysisStatsEval));
+		analysisData->stats= calloc(1, sizeof(AnalysisStatsEval));
 		analysisData->stats->broadcastDiffSum= 0.;
 
-		analysisData->stats->allStats= malloc(syncState->traceNb *
-			sizeof(TracePairStats*));
+		analysisData->stats->messageStats= malloc(syncState->traceNb *
+			sizeof(MessageStats*));
 		for (i= 0; i < syncState->traceNb; i++)
 		{
-			analysisData->stats->allStats[i]= calloc(syncState->traceNb,
-				sizeof(TracePairStats));
+			analysisData->stats->messageStats[i]= calloc(syncState->traceNb,
+				sizeof(MessageStats));
+		}
+
+		analysisData->stats->exchangeRtt=
+			g_hash_table_new_full(&ghfRttKeyHash, &gefRttKeyEqual,
+				&gdnDestroyRttKey, &gdnDestroyDouble);
+	}
+
+	if (syncState->graphs)
+	{
+		binBase= exp10(6. / (binNb - 2));
+		analysisData->graphs= malloc(sizeof(AnalysisGraphsEval));
+		initGraphs(syncState);
+	}
+}
+
+
+/*
+ * Create and open files used to store histogram points to genereate
+ * graphs. Allocate and populate array to store file pointers.
+ *
+ * Also create data structures to store histogram points during analysis.
+ *
+ * Args:
+ *   syncState:    container for synchronization data
+ */
+static void initGraphs(SyncState* const syncState)
+{
+	unsigned int i, j;
+	int retval;
+	char* cwd;
+	char name[36];
+	AnalysisDataEval* analysisData= syncState->analysisData;
+
+	cwd= changeToGraphDir(syncState->graphs);
+
+	analysisData->graphs->ttPoints= malloc(syncState->traceNb *
+		sizeof(FILE**));
+	analysisData->graphs->ttBinsArray= malloc(syncState->traceNb *
+		sizeof(uint32_t**));
+	analysisData->graphs->ttBinsTotal= malloc(syncState->traceNb *
+		sizeof(uint32_t*));
+	for (i= 0; i < syncState->traceNb; i++)
+	{
+		analysisData->graphs->ttPoints[i]= malloc(syncState->traceNb *
+			sizeof(FILE*));
+		analysisData->graphs->ttBinsArray[i]= malloc(syncState->traceNb *
+			sizeof(uint32_t*));
+		analysisData->graphs->ttBinsTotal[i]= calloc(syncState->traceNb,
+			sizeof(uint32_t));
+		for (j= 0; j < syncState->traceNb; j++)
+		{
+			if (i != j)
+			{
+				retval= snprintf(name, sizeof(name),
+					"analysis_eval_tt-%03u_to_%03u.data", i, j);
+				if (retval > sizeof(name) - 1)
+				{
+					name[sizeof(name) - 1]= '\0';
+				}
+				if ((analysisData->graphs->ttPoints[i][j]= fopen(name, "w")) ==
+					NULL)
+				{
+					g_error(strerror(errno));
+				}
+
+				analysisData->graphs->ttBinsArray[i][j]= calloc(binNb,
+					sizeof(uint32_t));
+			}
+		}
+	}
+
+	analysisData->graphs->hrttPoints= malloc(syncState->traceNb *
+		sizeof(FILE**));
+	analysisData->graphs->hrttBinsArray= malloc(syncState->traceNb *
+		sizeof(uint32_t**));
+	analysisData->graphs->hrttBinsTotal= malloc(syncState->traceNb *
+		sizeof(uint32_t*));
+	for (i= 0; i < syncState->traceNb; i++)
+	{
+		analysisData->graphs->hrttPoints[i]= malloc(i * sizeof(FILE*));
+		analysisData->graphs->hrttBinsArray[i]= malloc(i * sizeof(uint32_t*));
+		analysisData->graphs->hrttBinsTotal[i]= calloc(i, sizeof(uint32_t));
+		for (j= 0; j < i; j++)
+		{
+			retval= snprintf(name, sizeof(name),
+				"analysis_eval_hrtt-%03u_and_%03u.data", i, j);
+			if (retval > sizeof(name) - 1)
+			{
+				name[sizeof(name) - 1]= '\0';
+			}
+			if ((analysisData->graphs->hrttPoints[i][j]= fopen(name, "w")) ==
+				NULL)
+			{
+				g_error(strerror(errno));
+			}
+
+			analysisData->graphs->hrttBinsArray[i][j]= calloc(binNb,
+				sizeof(uint32_t));
+		}
+	}
+
+	retval= chdir(cwd);
+	if (retval == -1)
+	{
+		g_error(strerror(errno));
+	}
+	free(cwd);
+}
+
+
+/*
+ * Write histogram points to all files to generate graphs.
+ *
+ * Args:
+ *   syncState:    container for synchronization data
+ */
+static void writeGraphFiles(SyncState* const syncState)
+{
+	unsigned int i, j;
+	AnalysisDataEval* analysisData= syncState->analysisData;
+
+	for (i= 0; i < syncState->traceNb; i++)
+	{
+		for (j= 0; j < syncState->traceNb; j++)
+		{
+			if (i != j)
+			{
+				dumpBinToFile(analysisData->graphs->ttBinsArray[i][j],
+					analysisData->graphs->ttBinsTotal[i][j] -
+					analysisData->graphs->ttBinsArray[i][j][binNb - 1],
+					analysisData->graphs->ttPoints[i][j]);
+			}
+
+			if (i > j)
+			{
+				dumpBinToFile(analysisData->graphs->hrttBinsArray[i][j],
+					analysisData->graphs->hrttBinsTotal[i][j] -
+					analysisData->graphs->hrttBinsArray[i][j][binNb - 1],
+					analysisData->graphs->hrttPoints[i][j]);
+			}
+		}
+	}
+}
+
+
+/*
+ * Write the content of one bin in a histogram point file
+ *
+ * Args:
+ *   bin:          array of values that make up a histogram
+ *   total:        total number of messages in bins 0 to binNb - 2
+ *   file:         FILE*
+ */
+static void dumpBinToFile(const uint32_t* const bin, const uint32_t total,
+	FILE* const file)
+{
+	unsigned int i;
+
+	// Last bin is skipped because is continues till infinity
+	for (i= 0; i < binNb - 1; i++)
+	{
+		if (bin[i] > 0)
+		{
+			fprintf(file, "%20.9f %20.9f %20.9f\n", (binStart(i) + binEnd(i)) / 2, (double) bin[i]
+				/ ((binEnd(i) - binStart(i)) * total), binEnd(i) - binStart(i));
+		}
+	}
+}
+
+
+/*
+ * Close files used to store histogram points to generate graphs. Deallocate
+ * arrays of file pointers and arrays used to store histogram points during
+ * analysis.
+ *
+ * Args:
+ *   syncState:    container for synchronization data
+ */
+static void destroyGraphs(SyncState* const syncState)
+{
+	unsigned int i, j;
+	AnalysisDataEval* analysisData= syncState->analysisData;
+	int retval;
+
+	if (analysisData->graphs == NULL || analysisData->graphs->ttPoints ==
+		NULL)
+	{
+		return;
+	}
+
+	for (i= 0; i < syncState->traceNb; i++)
+	{
+		for (j= 0; j < syncState->traceNb; j++)
+		{
+			if (i != j)
+			{
+				retval= fclose(analysisData->graphs->ttPoints[i][j]);
+				if (retval != 0)
+				{
+					g_error(strerror(errno));
+				}
+
+				free(analysisData->graphs->ttBinsArray[i][j]);
+			}
+		}
+		free(analysisData->graphs->ttPoints[i]);
+		free(analysisData->graphs->ttBinsArray[i]);
+		free(analysisData->graphs->ttBinsTotal[i]);
+	}
+	free(analysisData->graphs->ttPoints);
+	free(analysisData->graphs->ttBinsArray);
+	free(analysisData->graphs->ttBinsTotal);
+
+	for (i= 0; i < syncState->traceNb; i++)
+	{
+		for (j= 0; j < i; j++)
+		{
+			retval= fclose(analysisData->graphs->hrttPoints[i][j]);
+			if (retval != 0)
+			{
+				g_error(strerror(errno));
+			}
+
+			free(analysisData->graphs->hrttBinsArray[i][j]);
 		}
+		free(analysisData->graphs->hrttPoints[i]);
+		free(analysisData->graphs->hrttBinsArray[i]);
+		free(analysisData->graphs->hrttBinsTotal[i]);
 	}
+	free(analysisData->graphs->hrttPoints);
+	free(analysisData->graphs->hrttBinsArray);
+	free(analysisData->graphs->hrttBinsTotal);
+
+	analysisData->graphs->ttPoints= NULL;
 }
 
 
@@ -174,12 +429,21 @@ static void destroyAnalysisEval(SyncState* const syncState)
 	{
 		for (i= 0; i < syncState->traceNb; i++)
 		{
-			free(analysisData->stats->allStats[i]);
+			free(analysisData->stats->messageStats[i]);
 		}
-		free(analysisData->stats->allStats);
+		free(analysisData->stats->messageStats);
+
+		g_hash_table_destroy(analysisData->stats->exchangeRtt);
+
 		free(analysisData->stats);
 	}
 
+	if (syncState->graphs && analysisData->graphs)
+	{
+		destroyGraphs(syncState);
+		free(analysisData->graphs);
+	}
+
 	free(syncState->analysisData);
 	syncState->analysisData= NULL;
 }
@@ -188,6 +452,8 @@ static void destroyAnalysisEval(SyncState* const syncState)
 /*
  * Perform analysis on an event pair.
  *
+ * Check if there is message inversion or messages that are too fast.
+ *
  * Args:
  *   syncState     container for synchronization data
  *   message       structure containing the events
@@ -195,29 +461,123 @@ static void destroyAnalysisEval(SyncState* const syncState)
 static void analyzeMessageEval(SyncState* const syncState, Message* const message)
 {
 	AnalysisDataEval* analysisData;
+	MessageStats* messageStats;
+	double* rtt;
+	double tt;
+	struct RttKey rttKey;
+
+	if (!syncState->stats)
+	{
+		return;
+	}
 
 	analysisData= (AnalysisDataEval*) syncState->analysisData;
+	messageStats=
+		&analysisData->stats->messageStats[message->outE->traceNum][message->inE->traceNum];
+
+	messageStats->total++;
+
+	tt= wallTimeSub(&message->inE->wallTime, &message->outE->wallTime);
+	if (tt <= 0)
+	{
+		messageStats->inversionNb++;
+	}
+	else if (syncState->graphs)
+	{
+		analysisData->graphs->ttBinsArray[message->outE->traceNum][message->inE->traceNum][binNum(tt)]++;
+		analysisData->graphs->ttBinsTotal[message->outE->traceNum][message->inE->traceNum]++;
+	}
+
+	g_assert(message->inE->type == TCP);
+	rttKey.saddr=
+		message->inE->event.tcpEvent->segmentKey->connectionKey.saddr;
+	rttKey.daddr=
+		message->inE->event.tcpEvent->segmentKey->connectionKey.daddr;
+	rtt= g_hash_table_lookup(analysisData->rttInfo, &rttKey);
+	g_debug("rttInfo, looking up (%u, %u)->(%f)", rttKey.saddr,
+		rttKey.daddr, rtt ? *rtt : NAN);
+
+	if (rtt)
+	{
+		g_debug("rttInfo, tt: %f rtt / 2: %f", tt, *rtt / 2.);
+		if (tt < *rtt / 2.)
+		{
+			messageStats->tooFastNb++;
+		}
+	}
+	else
+	{
+		messageStats->noRTTInfoNb++;
+	}
 }
 
 
 /*
  * Perform analysis on multiple messages
  *
+ * Measure the RTT
+ *
  * Args:
  *   syncState     container for synchronization data
  *   exchange      structure containing the messages
  */
 static void analyzeExchangeEval(SyncState* const syncState, Exchange* const exchange)
 {
-	AnalysisDataEval* analysisData;
+	AnalysisDataEval* analysisData= syncState->analysisData;
+	Message* m1= g_queue_peek_tail(exchange->acks);
+	Message* m2= exchange->message;
+	struct RttKey* rttKey;
+	double* rtt, * exchangeRtt;
 
-	analysisData= (AnalysisDataEval*) syncState->analysisData;
+	if (!syncState->stats)
+	{
+		return;
+	}
+
+	// (T2 - T1) - (T3 - T4)
+	rtt= malloc(sizeof(double));
+	*rtt= wallTimeSub(&m1->inE->wallTime, &m1->outE->wallTime) -
+		wallTimeSub(&m2->outE->wallTime, &m2->inE->wallTime);
+
+	if (syncState->graphs)
+	{
+		unsigned int row= MAX(m1->inE->traceNum, m1->outE->traceNum);
+		unsigned int col= MIN(m1->inE->traceNum, m1->outE->traceNum);
+
+		analysisData->graphs->hrttBinsArray[row][col][binNum(*rtt / 2.)]++;
+		analysisData->graphs->hrttBinsTotal[row][col]++;
+	}
+
+	g_assert(m1->inE->type == TCP);
+	rttKey= malloc(sizeof(struct RttKey));
+	rttKey->saddr=
+		MIN(m1->inE->event.tcpEvent->segmentKey->connectionKey.saddr,
+			m1->inE->event.tcpEvent->segmentKey->connectionKey.daddr);
+	rttKey->daddr=
+		MAX(m1->inE->event.tcpEvent->segmentKey->connectionKey.saddr,
+			m1->inE->event.tcpEvent->segmentKey->connectionKey.daddr);
+	exchangeRtt= g_hash_table_lookup(analysisData->stats->exchangeRtt,
+		rttKey);
+
+	if (exchangeRtt)
+	{
+		if (*rtt < *exchangeRtt)
+		{
+			g_hash_table_replace(analysisData->stats->exchangeRtt, rttKey, rtt);
+		}
+	}
+	else
+	{
+		g_hash_table_insert(analysisData->stats->exchangeRtt, rttKey, rtt);
+	}
 }
 
 
 /*
  * Perform analysis on muliple events
  *
+ * Sum the broadcast differential delays
+ *
  * Args:
  *   syncState     container for synchronization data
  *   broadcast     structure containing the events
@@ -225,8 +585,27 @@ static void analyzeExchangeEval(SyncState* const syncState, Exchange* const exch
 static void analyzeBroadcastEval(SyncState* const syncState, Broadcast* const broadcast)
 {
 	AnalysisDataEval* analysisData;
+	double sum= 0, squaresSum= 0;
+	double y;
+
+	if (!syncState->stats)
+	{
+		return;
+	}
 
 	analysisData= (AnalysisDataEval*) syncState->analysisData;
+
+	g_queue_foreach(broadcast->events, &gfSum, &sum);
+	g_queue_foreach(broadcast->events, &gfSumSquares, &squaresSum);
+
+	analysisData->stats->broadcastNb++;
+	// Because of numerical errors, this can at times be < 0
+	y= squaresSum / g_queue_get_length(broadcast->events) - pow(sum /
+		g_queue_get_length(broadcast->events), 2.);
+	if (y > 0)
+	{
+		analysisData->stats->broadcastDiffSum+= sqrt(y);
+	}
 }
 
 
@@ -240,12 +619,20 @@ static void analyzeBroadcastEval(SyncState* const syncState, Broadcast* const br
  *   syncState     container for synchronization data.
  *
  * Returns:
- *   Factors[traceNb] synchronization factors for each trace
+ *   Factors[traceNb] identity factors for each trace
  */
 static GArray* finalizeAnalysisEval(SyncState* const syncState)
 {
 	GArray* factors;
 	unsigned int i;
+	AnalysisDataEval* analysisData= syncState->analysisData;
+
+	if (syncState->graphs && analysisData->graphs)
+	{
+		writeGraphFiles(syncState);
+		destroyGraphs(syncState);
+		analysisData->graphs= NULL;
+	}
 
 	factors= g_array_sized_new(FALSE, FALSE, sizeof(Factors),
 		syncState->traceNb);
@@ -285,28 +672,83 @@ static void printAnalysisStatsEval(SyncState* const syncState)
 	printf("Synchronization evaluation analysis stats:\n");
 	printf("\tsum of broadcast differential delays: %g\n",
 		analysisData->stats->broadcastDiffSum);
+	printf("\taverage broadcast differential delays: %g\n",
+		analysisData->stats->broadcastDiffSum /
+		analysisData->stats->broadcastNb);
 
 	printf("\tIndividual evaluation:\n"
-		"\t\tTrace pair  Inversions  Too fast    (No RTT info)\n");
+		"\t\tTrace pair  Inversions Too fast   (No RTT info) Total\n");
 
 	for (i= 0; i < syncState->traceNb; i++)
 	{
 		for (j= i + 1; j < syncState->traceNb; j++)
 		{
-			TracePairStats* tpStats;
-			const char* format= "\t\t%3d - %-3d   %-10u  %-10u  %u\n";
+			MessageStats* messageStats;
+			const char* format= "\t\t%3d - %-3d   %-10u %-10u %-10u    %u\n";
+
+			messageStats= &analysisData->stats->messageStats[i][j];
+
+			printf(format, i, j, messageStats->inversionNb, messageStats->tooFastNb,
+				messageStats->noRTTInfoNb, messageStats->total);
+
+			messageStats= &analysisData->stats->messageStats[j][i];
+
+			printf(format, j, i, messageStats->inversionNb, messageStats->tooFastNb,
+				messageStats->noRTTInfoNb, messageStats->total);
+		}
+	}
+
+	printf("\tRound-trip times:\n"
+		"\t\tHost pair                          RTT from exchanges  RTTs from file (ms)\n");
+	g_hash_table_foreach(analysisData->stats->exchangeRtt,
+		&ghfPrintExchangeRtt, analysisData->rttInfo);
+}
+
+
+/*
+ * A GHFunc for g_hash_table_foreach()
+ *
+ * Args:
+ *   key:          RttKey* where saddr < daddr
+ *   value:        double*, RTT estimated from exchanges
+ *   user_data     GHashTable* rttInfo
+ */
+static void ghfPrintExchangeRtt(gpointer key, gpointer value, gpointer user_data)
+{
+	char addr1[16], addr2[16];
+	struct RttKey* rttKey1= key;
+	struct RttKey rttKey2= {rttKey1->daddr, rttKey1->saddr};
+	double* fileRtt1, *fileRtt2;
+	GHashTable* rttInfo= user_data;
 
-			tpStats= &analysisData->stats->allStats[i][j];
+	convertIP(addr1, rttKey1->saddr);
+	convertIP(addr2, rttKey1->daddr);
 
-			printf(format, i, j, tpStats->inversionNb, tpStats->tooFastNb,
-				tpStats->noRTTInfoNb);
+	fileRtt1= g_hash_table_lookup(rttInfo, rttKey1);
+	fileRtt2= g_hash_table_lookup(rttInfo, &rttKey2);
 
-			tpStats= &analysisData->stats->allStats[j][i];
+	printf("\t\t(%15s, %-15s) %-18.3f  ", addr1, addr2, *(double*) value * 1e3);
 
-			printf(format, j, i, tpStats->inversionNb, tpStats->tooFastNb,
-				tpStats->noRTTInfoNb);
+	if (fileRtt1 || fileRtt2)
+	{
+		if (fileRtt1)
+		{
+			printf("%.3f", *fileRtt1 * 1e3);
+		}
+		if (fileRtt1 && fileRtt2)
+		{
+			printf(", ");
 		}
+		if (fileRtt2)
+		{
+			printf("%.3f", *fileRtt2 * 1e3);
+		}
+	}
+	else
+	{
+		printf("-");
 	}
+	printf("\n");
 }
 
 
@@ -451,6 +893,9 @@ static void readRttInfo(GHashTable* rttInfo, FILE* rttStream)
 				addr.s_addr;
 		}
 
+		*rtt/= 1e3;
+		g_debug("rttInfo, Inserting (%u, %u)->(%f)", rttKey->saddr,
+			rttKey->daddr, *rtt);
 		g_hash_table_insert(rttInfo, rttKey, rtt);
 
 		positionStream(rttStream);
@@ -520,3 +965,176 @@ outEof:
 		free(line);
 	}
 }
+
+
+/*
+ * A GFunc for g_queue_foreach()
+ *
+ * Args:
+ *   data          Event*, a UDP broadcast event
+ *   user_data     double*, the running sum
+ *
+ * Returns:
+ *   Adds the time of the event to the sum
+ */
+static void gfSum(gpointer data, gpointer userData)
+{
+	Event* event= (Event*) data;
+
+	*(double*) userData+= event->wallTime.seconds + event->wallTime.nanosec /
+		1e9;
+}
+
+
+/*
+ * A GFunc for g_queue_foreach()
+ *
+ * Args:
+ *   data          Event*, a UDP broadcast event
+ *   user_data     double*, the running sum
+ *
+ * Returns:
+ *   Adds the square of the time of the event to the sum
+ */
+static void gfSumSquares(gpointer data, gpointer userData)
+{
+	Event* event= (Event*) data;
+
+	*(double*) userData+= pow(event->wallTime.seconds + event->wallTime.nanosec
+		/ 1e9, 2.);
+}
+
+
+/*
+ * Figure out the bin in a histogram to which a value belongs.
+ *
+ * This uses exponentially sized bins that go from 0 to infinity.
+ *
+ * Args:
+ *   value:        the value, must be >=0, or else expect the unexpected
+ *                 (floating point exception)
+ */
+static unsigned int binNum(const double value)
+{
+	if (value == 0)
+	{
+		return 0;
+	}
+	else
+	{
+		double result= floor(log(value) / log(binBase)) + (binNb - 1);
+
+		if (result < 0.)
+		{
+			return 0.;
+		}
+		else
+		{
+			return result;
+		}
+	}
+}
+
+
+/*
+ * Figure out the start of the interval of a bin in a histogram. The starting
+ * value is included in the interval.
+ *
+ * This uses exponentially sized bins that go from 0 to infinity.
+ *
+ * Args:
+ *   binNum:       bin number
+ */
+static double binStart(const unsigned int binNum)
+{
+	g_assert(binNum < binNb);
+
+	if (binNum == 0)
+	{
+		return 0;
+	}
+	else
+	{
+		return pow(binBase, (double) binNum - (binNb - 1));
+	}
+}
+
+
+/*
+ * Figure out the end of the interval of a bin in a histogram. The end value
+ * is not included in the interval.
+ *
+ * This uses exponentially sized bins that go from 0 to infinity.
+ *
+ * Args:
+ *   binNum:       bin number
+ */
+static double binEnd(const unsigned int binNum)
+{
+	g_assert(binNum < binNb);
+
+	if (binNum < binNb)
+	{
+		return pow(binBase, (double) binNum - (binNb - 2));
+	}
+	else
+	{
+		return INFINITY;
+	}
+}
+
+
+/*
+ * Write the analysis-specific graph lines in the gnuplot script.
+ *
+ * Args:
+ *   stream:       stream where to write the data
+ *   syncState:    container for synchronization data
+ *   i:            first trace number
+ *   j:            second trace number, garanteed to be larger than i
+ */
+static void writeAnalysisGraphsPlotsEval(FILE* stream, SyncState* const
+	syncState, const unsigned int i, const unsigned int j)
+{
+	fprintf(stream,
+		"\t\"analysis_eval_hrtt-%2$03d_and_%1$03d.data\" "
+			"title \"RTT/2\" with boxes linetype 1 linewidth 3 "
+			"linecolor rgb \"black\" fill transparent solid 0.75, \\\n"
+		/*"\t\"analysis_eval_tt-%1$03d_to_%2$03d.data\" "
+			"title \"%1$u to %2$u\" with boxes linetype 1 linewidth 3 "
+			"linecolor rgb \"black\" fill transparent solid 0.5, \\\n"
+		"\t\"analysis_eval_tt-%2$03d_to_%1$03d.data\" "
+			"title \"%2$u to %1$u\" with boxes linetype 1 linewidth 3 "
+			"linecolor rgb \"black\" fill transparent solid 0.25, \\\n"*/
+			, i, j);
+	/*
+	fprintf(stream,
+		"\t\"analysis_eval_hrtt-%2$03d_and_%1$03d.data\" "
+			"title \"RTT/2\" with linespoints linetype 1 linewidth 3 "
+			"linecolor rgb \"black\", \\\n"
+		"\t\"analysis_eval_tt-%1$03d_to_%2$03d.data\" "
+			"title \"%1$u to %2$u\" with linespoints linetype 1 linewidth 3 "
+			"linecolor rgb \"gray70\", \\\n"
+		"\t\"analysis_eval_tt-%2$03d_to_%1$03d.data\" "
+			"title \"%2$u to %1$u\" with linespoints linetype 1 linewidth 3 "
+			"linecolor rgb \"gray40\", \\\n", i, j);
+*/
+}
+
+
+/*
+ * Write the analysis-specific options in the gnuplot script.
+ *
+ * Args:
+ *   stream:       stream where to write the data
+ *   syncState:    container for synchronization data
+ *   i:            first trace number
+ *   j:            second trace number, garanteed to be larger than i
+ */
+static void writeAnalysisGraphsOptionsEval(FILE* stream, SyncState*
+    const syncState, const unsigned int i, const unsigned int j)
+{
+	fprintf(stream,
+		"set xlabel \"Message Latency (s)\"\n"
+		"set ylabel \"Proportion of messages per second\"\n");
+}