From 434b587afe41c19391821e7392005068fda76248 Mon Sep 17 00:00:00 2001
From: "dtucker@openbsd.org" <dtucker@openbsd.org>
Date: Fri, 7 Dec 2018 04:36:09 +0000
Subject: [PATCH] upstream: Fix calculation of initial bandwidth limits.
 Account for

written bytes before the initial timer check so that the first buffer written
is accounted.  Set the threshold after which the timer is checked such that
the limit starts being computed as soon as possible, ie after the second
buffer is written.  This prevents an initial burst of traffic and provides a
more accurate bandwidth limit.  bz#2927, ok djm.

OpenBSD-Commit-ID: ff3ef76e4e43040ec198c2718d5682c36b255cb6
---
 misc.c | 9 ++++-----
 misc.h | 6 ++++--
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/misc.c b/misc.c
index dd74c8d45..275e68141 100644
--- a/misc.c
+++ b/misc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.134 2018/11/16 03:26:01 djm Exp $ */
+/* $OpenBSD: misc.c,v 1.135 2018/12/07 04:36:09 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -1335,11 +1335,11 @@ bandwidth_limit_init(struct bwlimit *bw, u_int64_t kbps, size_t buflen)
 {
 	bw->buflen = buflen;
 	bw->rate = kbps;
-	bw->thresh = bw->rate;
+	bw->thresh = buflen;
 	bw->lamt = 0;
 	timerclear(&bw->bwstart);
 	timerclear(&bw->bwend);
-}	
+}
 
 /* Callback from read/write loop to insert bandwidth-limiting delays */
 void
@@ -1348,12 +1348,11 @@ bandwidth_limit(struct bwlimit *bw, size_t read_len)
 	u_int64_t waitlen;
 	struct timespec ts, rm;
 
+	bw->lamt += read_len;
 	if (!timerisset(&bw->bwstart)) {
 		monotime_tv(&bw->bwstart);
 		return;
 	}
-
-	bw->lamt += read_len;
 	if (bw->lamt < bw->thresh)
 		return;
 
diff --git a/misc.h b/misc.h
index bcae6a509..2dd61dc32 100644
--- a/misc.h
+++ b/misc.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.h,v 1.76 2018/11/16 03:26:01 djm Exp $ */
+/* $OpenBSD: misc.h,v 1.77 2018/12/07 04:36:09 dtucker Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -135,7 +135,9 @@ void		put_u32_le(void *, u_int32_t)
 
 struct bwlimit {
 	size_t buflen;
-	u_int64_t rate, thresh, lamt;
+	u_int64_t rate;		/* desired rate in kbit/s */
+	u_int64_t thresh;	/* threshold after which we'll check timers */
+	u_int64_t lamt;		/* amount written in last timer interval */
 	struct timeval bwstart, bwend;
 };