Index: scripts/xeno-test.in
===================================================================
--- scripts/xeno-test.in	(revision 1487)
+++ scripts/xeno-test.in	(working copy)
@@ -200,7 +200,7 @@
 	loudly ./run -- -T 120 $XENOT_SWITCHTEST '# switchtest'
     )
     (	cd `dirname $0`/../testsuite/switchbench
-	loudly ./run -- -p 10 -n -l 1000 $XENOT_SWITCHBENCH '# switchbench'
+	loudly ./run -- -h $XENOT_SWITCHBENCH '# switchbench'
     )
     (	cd `dirname $0`/../testsuite/cyclic
 	loudly ./run -- -p 10 -n -l 1000 $XENOT_CYCLIC '# cyclictest'
Index: src/testsuite/switchbench/switchbench.c
===================================================================
--- src/testsuite/switchbench/switchbench.c	(revision 1487)
+++ src/testsuite/switchbench/switchbench.c	(working copy)
@@ -8,6 +8,7 @@
 #include <sys/mman.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <math.h>
 #include <stdio.h>
 #include <string.h>
 #include <signal.h>
@@ -43,17 +44,42 @@
 	histogram[inabs < HISTOGRAM_CELLS ? inabs : HISTOGRAM_CELLS - 1]++;
 }
 
-void dump_histogram(void)
+void dump_stats(double sum, int total_hits)
 {
-       int n;
+	int n;
+	double avg, variance = 0;
 
-       for (n = 0; n < HISTOGRAM_CELLS; n++) {
-               long hits = histogram[n];
-               if (hits)
-                       fprintf(stderr, "%d - %d us: %ld\n", n, n + 1, hits);
-       }
+	avg = sum / total_hits;
+	for (n = 0; n < HISTOGRAM_CELLS; n++) {
+		long hits = histogram[n];
+		if (hits)
+			variance += hits * (n-avg) * (n-avg);
+	}
+
+	/* compute std-deviation (unbiased form) */
+	variance /= total_hits - 1;
+	// variance = sqrt(variance);
+	
+	printf("HSS| %9d| %10.3f| %10.3f\n", total_hits, avg, variance);
 }
 
+void dump_histogram(void)
+{
+	int n, total_hits = 0;
+	double sum = 0;
+	fprintf(stderr, "---|---range-|---samples\n");
+	for (n = 0; n < HISTOGRAM_CELLS; n++) {
+		long hits = histogram[n];
+		if (hits) {
+			total_hits += hits;
+			sum += n * hits;
+			fprintf(stderr, "HSD| %d - %d | %10ld\n",
+				n, n + 1, hits);
+		}
+	}
+	dump_stats(sum, total_hits);
+}
+
 void event(void *cookie)
 {
        int err;
@@ -180,8 +206,14 @@
                }
 
        if (sampling_period == 0)
-               sampling_period = 100000;       /* ns */
+               sampling_period = 100000;	/* ns */
 
+       if (nsamples <= 0) {
+	       fprintf(stderr, "disregarding -n <%lld>, using -n <100> us\n",
+		       nsamples);
+               nsamples = 100000;		/* ns */
+       }
+
        signal(SIGINT, SIG_IGN);
        signal(SIGTERM, SIG_IGN);