                 Chelsio N210 10Gb Ethernet Network Controller

                         Driver Release Notes for Linux

                                 Version 2.1.0

                                 March 8, 2005

CONTENTS
========
 INTRODUCTION
 FEATURES
 PERFORMANCE
 DRIVER MESSAGES
 KNOWN ISSUES
 SUPPORT


INTRODUCTION
============

 This document describes the Linux driver for Chelsio 10Gb Ethernet Network
 Controller. This driver supports the Chelsio N210 NIC and is backward
 compatible with the Chelsio N110 model 10Gb NICs. This driver supports AMD64
 and EM64T, and x86 systems.


FEATURES
========

 Adaptive Interrupts (adaptive-rx)
 ---------------------------------

  This feature provides an adaptive algorithm that adjusts the interrupt
  coalescing parameters, allowing the driver to dynamically adapt the latency
  settings to achieve the highest performance during various types of network
  load.

  The interface used to control this feature is ethtool. Please see the
  ethtool manpage for additional usage information.

  By default, adaptive-rx is disabled.
  To enable adaptive-rx:

      ethtool -C <interface> adaptive-rx on

  To disable adaptive-rx, use ethtool:

      ethtool -C <interface> adaptive-rx off

  After disabling adaptive-rx, the timer latency value will be set to 50us.
  You may set the timer latency after disabling adaptive-rx:

      ethtool -C <interface> rx-usecs <microseconds>

  An example to set the timer latency value to 100us on eth0:

      ethtool -C eth0 rx-usecs 100

  You may also provide a timer latency value while disabling adpative-rx:

      ethtool -C <interface> adaptive-rx off rx-usecs <microseconds>

  If adaptive-rx is disabled and a timer latency value is specified, the timer
  will be set to the specified value until changed by the user or until
  adaptive-rx is enabled.

  To view the status of the adaptive-rx and timer latency values:

      ethtool -c <interface>


 TCP Segmentation Offloading (TSO) Support
 -----------------------------------------

  This feature, also known as "large send", enables a system's protocol stack
  to offload portions of outbound TCP processing to a network interface card
  thereby reducing system CPU utilization and enhancing performance.

  The interface used to control this feature is ethtool version 1.8 or higher.
  Please see the ethtool manpage for additional usage information.

  By default, TSO is enabled.
  To disable TSO:

      ethtool -K <interface> tso off

  To enable TSO:

      ethtool -K <interface> tso on

  To view the status of TSO:

      ethtool -k <interface>


PERFORMANCE
===========

 The following information is provided as an example of how to change system
 parameters for "performance tuning" an what value to use. You may or may not
 want to change these system parameters, depending on your server/workstation
 application. Doing so is not warranted in any way by Chelsio Communications,
 and is done at "YOUR OWN RISK". Chelsio will not be held responsible for loss
 of data or damage to equipment.

 Your distribution may have a different way of doing things, or you may prefer
 a different method. These commands are shown only to provide an example of
 what to do and are by no means definitive.

 Making any of the following system changes will only last until you reboot
 your system. You may want to write a script that runs at boot-up which
 includes the optimal settings for your system.

  Setting PCI Latency Timer:
      setpci -d 1425:* 0x0c.l=0x0000F800

  Disabling TCP timestamp:
      sysctl -w net.ipv4.tcp_timestamps=0

  Disabling SACK:
      sysctl -w net.ipv4.tcp_sack=0

  Setting TCP read buffers (min/default/max):
      sysctl -w net.ipv4.tcp_rmem="10000000 10000000 10000000"

  Setting TCP write buffers (min/pressure/max):
      sysctl -w net.ipv4.tcp_wmem="10000000 10000000 10000000"

  Setting TCP buffer space (min/pressure/max):
      sysctl -w net.ipv4.tcp_mem="10000000 10000000 10000000"

  Setting large number of incoming connection requests (2.6.x only):
      sysctl -w net.ipv4.tcp_max_syn_backlog=3000

  Setting maximum receive socket buffer size:
      sysctl -w net.core.rmem_max=524287

  Setting maximum send socket buffer size:
      sysctl -w net.core.wmem_max=524287

  Setting default receive socket buffer size:
      sysctl -w net.core.rmem_default=524287

  Setting default send socket buffer size:
      sysctl -w net.core.wmem_default=524287

  Setting maximum option memory buffers:
      sysctl -w net.core.optmem_max=524287

  Setting maximum backlog (# of unprocessed packets before kernel drops):
      sysctl -w net.core.netdev_max_backlog=300000

  Set smp_affinity (on a multiprocessor system) to a single CPU:
      echo 00000001 > /proc/irq/<interrupt_number>/smp_affinity

  TCP window size for single connections:
   The receive buffer (RX_WINDOW) size must be at least as large as the
   Bandwidth-Delay Product of the communication link between the sender and
   receiver. Due to the variations of RTT, you may want to increase the buffer
   size up to 2 times the Bandwidth-Delay Product. Reference page 289 of
   "TCP/IP Illustrated, Volume 1, The Protocols" by W. Richard Stevens.
   At 10Gb speeds, use the following formula:
       RX_WINDOW >= 1.25MBytes * RTT(in milliseconds)
       Example for RTT with 100us: RX_WINDOW = (1,250,000 * 0.1) = 125,000
   RX_WINDOW sizes of 256KB - 512KB should be sufficient.
   Setting the min, max, and default receive buffer (RX_WINDOW) size:
       sysctl -w net.ipv4.tcp_rmem="<min> <default> <max>"

  TCP window size for multiple connections:
   The receive buffer (RX_WINDOW) size may be calculated the same as single
   connections, but should be divided by the number of connections. The
   smaller window prevents congestion and facilitates better pacing,
   especially if/when MAC level flow control does not work well or when it is
   not supported on the machine. Experimentation may be necessary to attain
   the correct value. This method is provided as a starting point fot the
   correct receive buffer size.
   Setting the min, max, and default receive buffer (RX_WINDOW) size is
   performed in the same manner as single connection.


DRIVER MESSAGES
===============

 The following messages are the most common messages logged by syslog. These
 may be found in /var/log/messages.

  Driver up:
     Chelsio Network Driver - version 2.1.0

  NIC detected:
     eth#: Chelsio N210 1x10GBaseX NIC (rev #), PCIX 133MHz/64-bit

  Link up:
     eth#: link is up at 10 Gbps, full duplex

  Link down:
     eth#: link is down


SUPPORT
=======

 If you have problems with the software or hardware, please contact our
 customer support team via email at support@chelsio.com or check our website
 at http://www.chelsio.com

===============================================================================

 Chelsio Communications
 370 San Aleso Ave.
 Suite 100
 Sunnyvale, CA 94085
 http://www.chelsio.com

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.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

 Copyright (c) 2003-2005 Chelsio Communications. All rights reserved.

===============================================================================
