From 91c33dcfd08be3c00f7993dfc27c71212d2e9c32 Mon Sep 17 00:00:00 2001
From: David Bar-On <61089727+davidBar-On@users.noreply.github.com>
Date: Fri, 4 Dec 2020 18:26:53 +0200
Subject: [PATCH] Bitrate throttling when burst is specified (#1090)

When the -b option specifies a burst value, throttling the bitrate does not work. This is because iperf_check_throttle() does not perform the check when burst value was defined.

This change removes the dependency of iperf_check_throttle() on the burst value and moves that check to the caller of that function. (Except for the call by send_timer_proc() which does not seem to be related to the change.)
---
 src/iperf_api.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/iperf_api.c b/src/iperf_api.c
index dad864b..64f83fb 100644
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -1539,7 +1539,7 @@ iperf_check_throttle(struct iperf_stream *sp, struct iperf_time *nowP)
     double seconds;
     uint64_t bits_per_second;
 
-    if (sp->test->done || sp->test->settings->rate == 0 || sp->test->settings->burst != 0)
+    if (sp->test->done || sp->test->settings->rate == 0)
         return;
     iperf_time_diff(&sp->result->start_time_fixed, nowP, &temp_time);
     seconds = iperf_time_in_secs(&temp_time);
@@ -1598,6 +1598,7 @@ iperf_send(struct iperf_test *test, fd_set *write_setP)
     register int multisend, r, streams_active;
     register struct iperf_stream *sp;
     struct iperf_time now;
+    int no_throttle_check;
 
     /* Can we do multisend mode? */
     if (test->settings->burst != 0)
@@ -1607,8 +1608,11 @@ iperf_send(struct iperf_test *test, fd_set *write_setP)
     else
         multisend = 1;	/* nope */
 
+    /* Should bitrate throttle be checked for every send */
+    no_throttle_check = test->settings->rate != 0 && test->settings->burst == 0;
+
     for (; multisend > 0; --multisend) {
-	if (test->settings->rate != 0 && test->settings->burst == 0)
+	if (no_throttle_check)
 	    iperf_time_now(&now);
 	streams_active = 0;
 	SLIST_FOREACH(sp, &test->streams, streams) {
@@ -1623,7 +1627,8 @@ iperf_send(struct iperf_test *test, fd_set *write_setP)
 		streams_active = 1;
 		test->bytes_sent += r;
 		++test->blocks_sent;
-		iperf_check_throttle(sp, &now);
+                if (no_throttle_check)
+		    iperf_check_throttle(sp, &now);
 		if (multisend > 1 && test->settings->bytes != 0 && test->bytes_sent >= test->settings->bytes)
 		    break;
 		if (multisend > 1 && test->settings->blocks != 0 && test->blocks_sent >= test->settings->blocks)
@@ -1633,7 +1638,7 @@ iperf_send(struct iperf_test *test, fd_set *write_setP)
 	if (!streams_active)
 	    break;
     }
-    if (test->settings->burst != 0) {
+    if (!no_throttle_check) {   /* Throttle check if was not checked for each send */
 	iperf_time_now(&now);
 	SLIST_FOREACH(sp, &test->streams, streams)
 	    if (sp->sender)