From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Sat, 13 Jun 2009 23:53:05 +0000 (-0400)
Subject: Fix test_looplen, use double-precition arithmetic
X-Git-Tag: v0.1~146
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=85d2a666dfa980fec205a4bce7f6b53cdbed83c0;p=userspace-rcu.git

Fix test_looplen, use double-precition arithmetic

Here you go!!!

        [root@perfsqh userspace-rcu]# ./test_looplen
        CALIBRATION : 0 cycles per loop

Hmmm...  Probably not what you had in mind.  Breaking out the
floating-point arithmetic:

        [root@perfsqh userspace-rcu]# ./test_looplen
        CALIBRATION : 0.386172 cycles per loop
        time_tot = 4049312, LOOPS = 1048576, TESTS = 10

More helpful?  ;-)

                                                Thanx, Paul

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
---

diff --git a/test_looplen.c b/test_looplen.c
index 86d0386..e07409a 100644
--- a/test_looplen.c
+++ b/test_looplen.c
@@ -71,6 +71,7 @@ int main(int argc, char **argv)
 	unsigned long i;
 	cycles_t time1, time2;
 	cycles_t time_tot = 0;
+	double cpl;
 
 	for (i = 0; i < TESTS; i++) {
 		time1 = get_cycles();
@@ -78,10 +79,11 @@ int main(int argc, char **argv)
 		time2 = get_cycles();
 		time_tot += time2 - time1;
 	}
-	time_tot /= TESTS;
-	time_tot /= LOOPS;
+	cpl = ((double)time_tot) / (double)TESTS / (double)LOOPS;
 
-	printf("CALIBRATION : %llu cycles per loop\n", time_tot);
+	printf("CALIBRATION : %g cycles per loop\n", cpl);
+	printf("time_tot = %llu, LOOPS = %d, TESTS = %d\n",
+	       time_tot, LOOPS, TESTS);
 
 	return 0;
 }