From: Niels Möller <nisse@lysator.liu.se>
Date: Tue, 2 Jun 2020 05:27:59 +0000 (+0200)
Subject: Delete benchmark code attempting to measure function call overhead.
X-Git-Tag: nettle_3.7rc1~111
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=d420aa762c4eb64fcd9b89096f2e7312090f8fac;p=thirdparty%2Fnettle.git

Delete benchmark code attempting to measure function call overhead.
---

diff --git a/ChangeLog b/ChangeLog
index 16fcb467..1cf3e940 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2020-06-02  Niels Möller  <nisse@lysator.liu.se>
+
+	* examples/nettle-benchmark.c (main): Delete call to
+	time_overhead. The attempt to measure function call overhead is
+	not very useful or accurate. The benchmarking loop is optimized
+	away by gcc-10, making the benchmark program hang.
+	(bench_nothing, time_overhead): Deleted.
+
 2020-04-29  Niels Möller  <nisse@lysator.liu.se>
 
 	* Released Nettle-3.6.
diff --git a/examples/nettle-benchmark.c b/examples/nettle-benchmark.c
index 5d0e649e..69e34bfd 100644
--- a/examples/nettle-benchmark.c
+++ b/examples/nettle-benchmark.c
@@ -152,12 +152,6 @@ time_function(void (*f)(void *arg), void *arg)
   return elapsed / ncalls - overhead;
 }
 
-static void
-bench_nothing(void *arg UNUSED)
-{
-  return;
-}
-
 struct bench_memxor_info
 {
   void *dst;
@@ -333,17 +327,6 @@ xalloc(size_t size)
   return p;
 }
 
-static void
-time_overhead(void)
-{
-  overhead = time_function(bench_nothing, NULL);
-  printf("benchmark call overhead: %7f us", overhead * 1e6);
-  if (frequency > 0.0)
-    printf("%7.2f cycles\n", overhead * frequency);
-  printf("\n");  
-}
-
-
 
 static void
 time_memxor(void)
@@ -991,7 +974,6 @@ main(int argc, char **argv)
   bench_salsa20_core();
   bench_sha3_permute();
   printf("\n");
-  time_overhead();
 
   header();