Linux Driver for the Inte PRO/10GbE Server Adapters

# Linux* Base Driver for Intel® PRO/10GbE Server Adapters

Overview

Identifying Your Adapter

Building and Installation

Command Line Parameters

Improving Performance

Additional Configurations

Known Issues

## Overview

This file describes the Linux* Base Driver for the Intel® PRO/10GbE Server Adapter, version 1.0.x. This driver supports the 2.4.x and 2.6.x kernels. This driver includes support for ItaniumŪ2-based systems.
This driver is only supported as a loadable module at this time. Intel is not supplying patches against the kernel source to allow for static linking of the driver. For questions related to hardware requirements, refer to the documentation supplied with your Intel adapter. All hardware requirements listed apply to use with Linux.
Native VLANs are now available with supported kernels.
The driver information previously displayed in the /proc filesystem is not supported in this release. Alternatively, you can use ethtool (version 1.6 or later), lspci, and ifconfig to obtain the same information. Instructions on updating ethtool can be found in the section "Additional Configurations" later in this document.

## Identifying Your Adapter

The following Intel network adapters are compatible with the drivers in this release:

Controller | Adapter Name | Physical Layer
82597EX | Intel(R) PRO/10GbE LR/SR | 10G Base -LR and -SR Server Adapters (1310 and 850 nm optical fiber)

For more information on how to identify your adapter, go to the Adapter & Driver ID Guide at:

> http://support.intel.com/support/network/sb/CS-012904.htm

For the latest Intel network drivers for Linux, refer to the following website. In the search field, enter your adapter name or type, or use the networking link on the left to search for your adapter:

> http://downloadfinder.intel.com/scripts-df/support_intel.asp

## Building and Installation

To build a binary RPM* package of this driver, run 'rpmbuild -tb <filename.tar.gz>'. Replace <filename.tar.gz> with the specific file name of the driver.

| NOTE: For the build to work properly, the currently running kernel MUST match the version and configuration of the installed kernel sources. If you have just recompiled the kernel reboot the system now. RPM functionality has only been tested in Red Hat distributions.

To manually build this driver:

1. Move the base driver tar file to the directory of your choice. For example, use '/home/username/ixgb' or '/usr/local/src/ixgb'.

2. Untar/unzip the archive:

   > tar zxf ixgb-x.x.x.tar.gz

3. Change to the driver src directory:

   > cd ixgb-x.x.x/src/

4. Compile the driver module:

   > make install

   The binary will be installed as:

   > /lib/modules/[KERNEL_VERSION]/kernel/drivers/net/ixgb.[k]o

   The install locations listed above are the default locations. They might not be correct for certain Linux distributions. For more information, see the ldistrib.txt file included in the driver tar.

5. Load the module:
   For kernel 2.4.x, use the insmod command -
   insmod ixgb <parameter>=<value>
   For kernel 2.6.x, use the modprobe command -
   modprobe ixgb <parameter>=<value>

6. Assign an IP address to the interface by entering the following, where x is the interface number:

   > ifconfig ethx <IP_address>

7. Verify that the interface works. Enter the following, where <IP_address> is the IP address of another machine on the same subnet as the interface that is being tested:

   > ping <IP_address>

## Command Line Parameters

If the driver is built as a module, the following optional parameters are used by entering them on the command line with the modprobe or insmod command using this syntax:

> modprobe ixgb [<option>=<VAL1>,<VAL2>,...]

> insmod ixgb [<option>=<VAL1>,<VAL2>,...]

For example, with two PRO/10GbE PCI adapters, entering:

> insmod ixgb TxDescriptors=80,128

loads the ixgb driver with 80 TX resources for the first adapter and 128 TX resources for the second adapter.

The default value for each parameter is generally the recommended setting, unless otherwise noted.

Parameter Name | Valid Range/Settings | Default | Description
--- | --- | --- | ---
FlowControl | 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx) | Read flow control settings from the EEPROM | This parameter controls the automatic generation(Tx) and response(Rx) to Ethernet PAUSE frames.
RxDescriptors | 64-512 | 512 | This value is the number of receive descriptors allocated by the driver. Increasing this value allows the driver to buffer more incoming packets. Each descriptor is 16 bytes. A receive buffer is also allocated for each descriptor and can be either 2048, 4056, 8192, or 16384 bytes, depending on the MTU setting. When the MTU size is 1500 or less, the receive buffer size is 2048 bytes. When the MTU is greater than 1500 the receive buffer size will be either 4056, 8192, or 16384 bytes. The maximum MTU size is 16114.
RxIntDelay | 0-65535 (0=off) | 72 | This value delays the generation of receive interrupts in units of 0.8192 microseconds. Receive interrupt reduction can improve CPU efficiency if properly tuned for specific network traffic. Increasing this value adds extra latency to frame reception and can end up decreasing the throughput of TCP traffic. If the system is reporting dropped receives, this value may be set too high, causing the driver to run out of available receive descriptors.
TxDescriptors | 64-4096 | 256 | This value is the number of transmit descriptors allocated by the driver. Increasing this value allows the driver to queue more transmits. Each descriptor is 16 bytes.
XsumRX | 0-1 | 1 | A value of '1' indicates that the driver should enable IP checksum offload for received packets (both UDP and TCP) to the adapter hardware.

## Improving Performance

With the Intel PRO/10 GbE adapter, the default Linux configuration will very likely limit the total available throughput artificially. There is a set of things that when applied together increase the ability of Linux to transmit and receive data. The following enhancements were originally acquired from settings published at http://www.spec.org/web99/ for various submitted results using Linux.

| NOTE: These changes are only suggestions, and serve as a starting point for tuning your network performance.

The changes are made in three major ways, listed in order of greatest effect:
- Use ifconfig to modify the mtu (maximum transmission unit) and the txqueuelen parameter.
- Use sysctl to modify /proc parameters (essentially kernel tuning)
- Use setpci to modify the MMRBC field in PCI-X configuration space to increase transmit burst lengths on the bus.

| NOTE: setpci modifies the adapter's configuration registers to allow it to read up to 4k bytes at a time (for transmits). However, for some systems the behavior after modifying this register may be undefined (possibly errors of some kind). A power-cycle, hard reset or explicitly setting the e6 register back to 22 (setpci -d 8086:1a48 e6.b=22) may be required to get back to a stable configuration.

- COPY these lines and paste them into ixgb_perf.sh:
#!/bin/bash
echo "configuring network performance , edit this file to change the interface
or device ID of 10GbE card"
# set mmrbc to 4k reads, modify only Intel 10GbE device IDs
# replace 1a48 with appropriate 10GbE device's ID installed on the system, if needed.
# 8086:1a48 is the Intel SR adapter
setpci -d 8086:1a48 e6.b=2e
# set the MTU (max transmission unit) - it requires your switch and clients to change too!
# set the txqueuelen
# your ixgb adapter should be loaded as eth1 for this to work, change if needed
ifconfig eth1 mtu 9000 txqueuelen 1000 up
# call the sysctl utility to modify /proc/sys entries
sysctl -p ./sysctl_ixgb.conf
- END ixgb_perf.sh
- COPY these lines and paste them into sysctl_ixgb.conf:
# some of the defaults may be different for your kernel
# call this file with sysctl -p <this file>
# these are just suggested values that worked well to increase throughput in
# several network benchmark tests, your mileage may vary
### IPV4 specific settings
net.ipv4.tcp_timestamps = 0 # turns TCP timestamp support off, default 1, reduces CPU use
net.ipv4.tcp_sack = 0 # turn SACK support off, default on
# on systems with a VERY fast bus -> memory interface this is the big gainer
net.ipv4.tcp_rmem = 10000000 10000000 10000000 # sets min/default/max TCP read buffer, default 4096 87380 174760
net.ipv4.tcp_wmem = 10000000 10000000 10000000 # sets min/pressure/max TCP write buffer, default 4096 16384 131072
net.ipv4.tcp_mem = 10000000 10000000 10000000 # sets min/pressure/max TCP buffer space, default 31744 32256 32768
### CORE settings (mostly for socket and UDP effect)
net.core.rmem_max = 524287 # maximum receive socket buffer size, default 131071
net.core.wmem_max = 524287 # maximum send socket buffer size, default 131071
net.core.rmem_default = 524287 # default receive socket buffer size, default 65535
net.core.wmem_default = 524287 # default send socket buffer size, default 65535
net.core.optmem_max = 524287 # maximum amount of option memory buffers, default 10240
net.core.netdev_max_backlog = 300000 # number of unprocessed input packets before kernel starts dropping them, default 300
- END sysctl_ixgb.conf
Edit the ixgb_perf.sh script if necessary to change eth1 to whatever interface your ixgb driver is using and/or replace '1a48' with appropriate 10GbE device's ID installed on the system.

| NOTE: Unless these scripts are added to the boot process, these changes will only last only until the next system reboot.

### Resolving Slow UDP Traffic

If your server does not seem to be able to receive UDP traffic as fast as it can receive TCP traffic, it could be because Linux, by default, does not set the network stack buffers as large as they need to be to support high UDP transfer rates. One way to alleviate this problem is to allow more memory to be used by the IP stack to store incoming data.

For instance, use the commands:
sysctl -w net.core.rmem_max=262143
and
sysctl -w net.core.rmem_default=262143
to increase the read buffer memory max and default to 262143 (256k - 1) from defaults of max=131071 (128k - 1) and default=65535 (64k - 1). These variables will increase the amount of memory used by the network stack for receives, and can be increased significantly more if necessary for your application.

## Additional Configurations

### Configuring the Driver on Different Distributions

Configuring a network driver to load properly when the system is started is distribution dependent. Typically, the configuration process involves adding an alias line to /etc/modules.conf as well as editing other system startup scripts and/or configuration files. Many popular Linux distributions ship with tools to make these changes for you. To learn the proper way to configure a network device for your system, refer to your distribution documentation. If during this process you are asked for the driver or module name, the name for the Linux Base Driver for the Intel PRO/10GbE Family of Adapters is ixgb.

### Viewing Link Messages

Link messages will not be displayed to the console if the distribution is restricting system messages. In order to see network driver link messages on your console, set dmesg to eight by entering the following:

dmesg -n 8

| NOTE: This setting is not saved across reboots.

### Jumbo Frames

The driver supports Jumbo Frames for all adapters. Jumbo Frames support is enabled by changing the MTU to a value larger than the default of 1500. The maximum value for the MTU is 16114. Use the ifconfig command to increase the MTU size. For example, enter the following where <x> is the interface number:

> ifconfig ethx mtu 9000 up

The maximum MTU setting for Jumbo Frames is 16114. This value coincides with the maximum Jumbo Frames size of 16128.

### Ethtool

The driver utilizes the ethtool interface for driver configuration and diagnostics, as well as displaying statistical information. Ethtool version 1.6 or later is required for this functionality.
The latest release of ethtool can be found from http://sf.net/projects/gkernel.

### NAPI

NAPI (Rx polling mode) is supported in the ixgb driver. NAPI is enabled or disabled based on the configuration of the kernel. To override the default, use the following compile-time flags.

To enable NAPI, compile the driver module, passing in a configuration option:

make CFLAGS_EXTRA=-DIXGB_NAPI install

To disable NAPI, compile the driver module, passing in a configuration option:
make CFLAGS_EXTRA=-DIXGB_NO_NAPI install

See www.cyberus.ca/~hadi/usenix-paper.tgz for more information on NAPI.

## Known Issues

| NOTE: For distribution-specific information, see ldistrib.htm included in the driver tar.

### Driver Compilation

When trying to compile the driver by running make install, the following error may occur: "Linux kernel source not configured - missing version.h"

To solve this issue, create the version.h file by going to the Linux source tree and entering:

> make include/linux/version.h

### Jumbo Frames System Requirement

Memory allocation failures have been observed on Linux systems with 64 MB of RAM or less that are running Jumbo Frames. If you are using Jumbo Frames, your system may require more than the advertised minimum requirement of 64 MB of system memory.

### Performance Degradation with Jumbo Frames

Degradation in throughput performance may be observed in some Jumbo frames environments. If this is observed, increasing the application's socket buffer size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help. See the specific application manual and /usr/src/linux*/Documentation/networking/ip-sysctl.txt for more details.

### Multiple Interfaces on Same Ethernet Broadcast Network

Due to the ARP behavior on Linux, it is not possible to have one system on two IP networks in the same Ethernet broadcast domain (non-partitioned switch) behave as expected. All Ethernet interfaces will respond to IP traffic for any IP address assigned to the system. This results in unbalanced receive traffic.

If you have multiple interfaces in a server, either turn on ARP filtering by entering:

echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter

(this only works if your kernel's version is higher than 2.4.5), or install the interfaces in separate broadcast domains (either in different switches or in a switch partitioned to VLANs).

## Support

For general information, go to the Intel support website at:

http://support.intel.com

If an issue is identified with the released source code on the supported kernel with a supported adapter, email the specific information related to the issue to linux.nics@intel.com.

## License

This software program is released under the terms of a license agreement between you ('Licensee') and Intel. Do not use or load this software or any associated materials (collectively, the 'Software') until you have carefully read the full terms and conditions of the LICENSE located in this software package. By loading or using the Software, you agree to the terms of this Agreement. If you do not agree with the terms of this Agreement, do not install or use the Software.

`Last modified on 3/08/05 10:12a 10/22/04 9:45a 6`