From 49d4456f54d7a73ae06276f2ebf58e5f6f3039de Mon Sep 17 00:00:00 2001
From: Stephen Hemminger <stephen.hemminger@vyatta.com>
Date: Wed, 20 May 2009 16:46:24 -0700
Subject: Fix calculation of RED parameters

The latency value is in microseconds.
---
 lib/Vyatta/Qos/ShaperClass.pm | 3 ++-
 lib/Vyatta/Qos/Util.pm        | 8 ++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/Vyatta/Qos/ShaperClass.pm b/lib/Vyatta/Qos/ShaperClass.pm
index 482ec09..d89dfb9 100644
--- a/lib/Vyatta/Qos/ShaperClass.pm
+++ b/lib/Vyatta/Qos/ShaperClass.pm
@@ -159,7 +159,8 @@ sub fifoQdisc {
 sub redQdisc {
     my ( $self, $dev, $rate ) = @_;
     my $avg = 1000;
-    my ($qmin, $qmax, $burst) = RedParam($rate, 500, $avg);
+    my $latency = 100000;	# 100 ms
+    my ($qmin, $qmax, $burst) = RedParam($rate, $latency, $avg);
 
     my $limit = $self->{_limit};
     my $qlimit;
diff --git a/lib/Vyatta/Qos/Util.pm b/lib/Vyatta/Qos/Util.pm
index 2e0eec9..afd5c78 100644
--- a/lib/Vyatta/Qos/Util.pm
+++ b/lib/Vyatta/Qos/Util.pm
@@ -322,16 +322,16 @@ sub ethtoolRate {
 # Compute parameters for RED algorithim based on bandwidth and latency
 #
 #                       Bandwidth (bits/sec) * Latency (ms)
-# Maximum Threshold = --------------------------------------
-#                                1000 ms/sec
+# Maximum Threshold = -------------------------------------- 
+#   (bytes)                   8 bits/byte *  1000000 us/sec
 #
 # Minimum Threshold = Maximum Threshold / 3
 # Avpkt = Average Packet Length
 # Burst = ( 2 * MinThreshold + MaxThreshold) / ( 3 * Avpkt )
 # Limit = 4 * MaxThreshold
 sub RedParam {
-    my ($bandwidth, $latency, $avgpkt) = @_;
-    my $qmax = ($bandwidth * $latency) / 1000;
+    my ( $bandwidth, $latency, $avgpkt ) = @_;
+    my $qmax = ( $bandwidth * $latency ) / 8000000;
     my $qmin = $qmax / 3;
     my $burst = ( 2 * $qmin + $qmax ) / ( 3 * $avgpkt );
 
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