Bugfix 4428: Disable copybreak in selected drivers to improve performance.

2 files changed, 47 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
index e3a4d06..f7096af 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,6 +3,7 @@ share_perl5dir = /opt/vyatta/share/perl5/Vyatta
 completiondir	 = /etc/bash_completion.d
 initddir	 = /etc/init.d
 defaultdir = /etc/default
+modprobedir = /etc/modprobe.d
 etc_shell_leveldir = $(sysconfdir)/shell/level
 dhcphookdir = /etc/dhcp3/dhclient-exit-hooks.d
 
@@ -13,6 +14,7 @@ AM_LFLAGS = --prefix=yy_`basename $* .l`_ -olex.yy.c
 completion_SCRIPTS = etc/bash_completion.d/20vyatta-cfg
 initd_SCRIPTS	= etc/init.d/vyatta-ofr
 dhcphook_SCRIPTS = scripts/vyatta-dhclient-hook
+modprobe_SCRIPTS = etc/modprobe.d/vyatta_nocopybreak
 
 lib_LTLIBRARIES = src/libvyatta-cfg.la
 src_libvyatta_cfg_la_LIBADD = /usr/lib/libglib-2.0.la
diff --git a/etc/modprobe.d/vyatta_nocopybreak b/etc/modprobe.d/vyatta_nocopybreak
new file mode 100644
index 0000000..deb962f
--- /dev/null
+++ b/etc/modprobe.d/vyatta_nocopybreak
@@ -0,0 +1,45 @@
+# 
+# **** License ****
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+# 
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+# 
+# This code was originally developed by Vyatta, Inc.
+# Portions created by Vyatta are Copyright (C) 2009 Vyatta, Inc.
+# All Rights Reserved.
+# **** End License ****
+# 
+# Author:  Bob Gilligan <gilligan@vyatta.com>
+# 
+# Some network interface drivers employ a scheme known as "copybreak"
+# in which they make a copy of a received skb if the size of the
+# buffer is below a particular threshold, then return the original
+# receive skb back to the pool.  Since these drivers initially
+# allocate a buffer size that is larger than the largest possible
+# packet, this scheme returns that large buffer to the pool quickly,
+# and uses a smaller one. 
+# 
+# The primary benefit of copybreak is better memory utilization.  On
+# systems where the data is ultimately going to be copied out to user
+# space, the copybreak scheme is "low cost" because it has the side
+# benefit of priming the cache for that later copy.  But on a router
+# that only touches the header fields of a received packet, the cost
+# can be relatively higher.  And on modern systems the memory savings
+# is rarely an important consideration.
+# 
+# Some of the drivers that employ copybreak make the feature
+# configurable via a module parameter.  This file disables copybreak
+# in some of those drivers.  Generally this results in an improvement
+# in forwarding performance for traffic using these drivers.
+#
+
+options e1000 copybreak=0
+options e1000e copybreak=0
+
+
+