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linux/Documentation/networking/e1000.txt
Francois Romieu c3570acb53 e1000: delete non NAPI code from the driver 
Compile-tested only.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
2008-07-22 19:39:11 -04:00

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Linux* Base Driver for the Intel(R) PRO/1000 Family of Adapters
===============================================================
September 26, 2006
Contents
========
- In This Release
- Identifying Your Adapter
- Building and Installation
- Command Line Parameters
- Speed and Duplex Configuration
- Additional Configurations
- Known Issues
- Support
In This Release
===============
This file describes the Linux* Base Driver for the Intel(R) PRO/1000 Family
of Adapters. This driver includes support for Itanium(R)2-based systems.
For questions related to hardware requirements, refer to the documentation
supplied with your Intel PRO/1000 adapter. All hardware requirements listed
apply to use with Linux.
The following features are now available in supported kernels:
- Native VLANs
- Channel Bonding (teaming)
- SNMP
Channel Bonding documentation can be found in the Linux kernel source:
/Documentation/networking/bonding.txt
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.
NOTE: The Intel(R) 82562v 10/100 Network Connection only provides 10/100
support.
Identifying Your Adapter
========================
For more information on how to identify your adapter, go to the Adapter &
Driver ID Guide at:
http://support.intel.com/support/network/adapter/pro100/21397.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
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 command
using this syntax:
modprobe e1000 [<option>=<VAL1>,<VAL2>,...]
For example, with two PRO/1000 PCI adapters, entering:
modprobe e1000 TxDescriptors=80,128
loads the e1000 driver with 80 TX descriptors for the first adapter and
128 TX descriptors for the second adapter.
The default value for each parameter is generally the recommended setting,
unless otherwise noted.
NOTES: For more information about the AutoNeg, Duplex, and Speed
parameters, see the "Speed and Duplex Configuration" section in
this document.
For more information about the InterruptThrottleRate,
RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
parameters, see the application note at:
http://www.intel.com/design/network/applnots/ap450.htm
A descriptor describes a data buffer and attributes related to
the data buffer. This information is accessed by the hardware.
AutoNeg
-------
(Supported only on adapters with copper connections)
Valid Range: 0x01-0x0F, 0x20-0x2F
Default Value: 0x2F
This parameter is a bit-mask that specifies the speed and duplex settings
advertised by the adapter. When this parameter is used, the Speed and
Duplex parameters must not be specified.
NOTE: Refer to the Speed and Duplex section of this readme for more
information on the AutoNeg parameter.
Duplex
------
(Supported only on adapters with copper connections)
Valid Range: 0-2 (0=auto-negotiate, 1=half, 2=full)
Default Value: 0
This defines the direction in which data is allowed to flow. Can be
either one or two-directional. If both Duplex and the link partner are
set to auto-negotiate, the board auto-detects the correct duplex. If the
link partner is forced (either full or half), Duplex defaults to half-
duplex.
FlowControl
-----------
Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx)
Default Value: Reads flow control settings from the EEPROM
This parameter controls the automatic generation(Tx) and response(Rx)
to Ethernet PAUSE frames.
InterruptThrottleRate
---------------------
(not supported on Intel(R) 82542, 82543 or 82544-based adapters)
Valid Range: 0,1,3,100-100000 (0=off, 1=dynamic, 3=dynamic conservative)
Default Value: 3
The driver can limit the amount of interrupts per second that the adapter
will generate for incoming packets. It does this by writing a value to the
adapter that is based on the maximum amount of interrupts that the adapter
will generate per second.
Setting InterruptThrottleRate to a value greater or equal to 100
will program the adapter to send out a maximum of that many interrupts
per second, even if more packets have come in. This reduces interrupt
load on the system and can lower CPU utilization under heavy load,
but will increase latency as packets are not processed as quickly.
The default behaviour of the driver previously assumed a static
InterruptThrottleRate value of 8000, providing a good fallback value for
all traffic types,but lacking in small packet performance and latency.
The hardware can handle many more small packets per second however, and
for this reason an adaptive interrupt moderation algorithm was implemented.
Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which
it dynamically adjusts the InterruptThrottleRate value based on the traffic
that it receives. After determining the type of incoming traffic in the last
timeframe, it will adjust the InterruptThrottleRate to an appropriate value
for that traffic.
The algorithm classifies the incoming traffic every interval into
classes. Once the class is determined, the InterruptThrottleRate value is
adjusted to suit that traffic type the best. There are three classes defined:
"Bulk traffic", for large amounts of packets of normal size; "Low latency",
for small amounts of traffic and/or a significant percentage of small
packets; and "Lowest latency", for almost completely small packets or
minimal traffic.
In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
latency" or "Lowest latency" class, the InterruptThrottleRate is increased
stepwise to 20000. This default mode is suitable for most applications.
For situations where low latency is vital such as cluster or
grid computing, the algorithm can reduce latency even more when
InterruptThrottleRate is set to mode 1. In this mode, which operates
the same as mode 3, the InterruptThrottleRate will be increased stepwise to
70000 for traffic in class "Lowest latency".
Setting InterruptThrottleRate to 0 turns off any interrupt moderation
and may improve small packet latency, but is generally not suitable
for bulk throughput traffic.
NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
RxAbsIntDelay parameters. In other words, minimizing the receive
and/or transmit absolute delays does not force the controller to
generate more interrupts than what the Interrupt Throttle Rate
allows.
CAUTION: If you are using the Intel(R) PRO/1000 CT Network Connection
(controller 82547), setting InterruptThrottleRate to a value
greater than 75,000, may hang (stop transmitting) adapters
under certain network conditions. If this occurs a NETDEV
WATCHDOG message is logged in the system event log. In
addition, the controller is automatically reset, restoring
the network connection. To eliminate the potential for the
hang, ensure that InterruptThrottleRate is set no greater
than 75,000 and is not set to 0.
NOTE: When e1000 is loaded with default settings and multiple adapters
are in use simultaneously, the CPU utilization may increase non-
linearly. In order to limit the CPU utilization without impacting
the overall throughput, we recommend that you load the driver as
follows:
modprobe e1000 InterruptThrottleRate=3000,3000,3000
This sets the InterruptThrottleRate to 3000 interrupts/sec for
the first, second, and third instances of the driver. The range
of 2000 to 3000 interrupts per second works on a majority of
systems and is a good starting point, but the optimal value will
be platform-specific. If CPU utilization is not a concern, use
RX_POLLING (NAPI) and default driver settings.
RxDescriptors
-------------
Valid Range: 80-256 for 82542 and 82543-based adapters
80-4096 for all other supported adapters
Default Value: 256
This value specifies the number of receive buffer descriptors allocated
by the driver. Increasing this value allows the driver to buffer more
incoming packets, at the expense of increased system memory utilization.
Each descriptor is 16 bytes. A receive buffer is also allocated for each
descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending
on the MTU setting. The maximum MTU size is 16110.
NOTE: MTU designates the frame size. It only needs to be set for Jumbo
Frames. Depending on the available system resources, the request
for a higher number of receive descriptors may be denied. In this
case, use a lower number.
RxIntDelay
----------
Valid Range: 0-65535 (0=off)
Default Value: 0
This value delays the generation of receive interrupts in units of 1.024
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.
CAUTION: When setting RxIntDelay to a value other than 0, adapters may
hang (stop transmitting) under certain network conditions. If
this occurs a NETDEV WATCHDOG message is logged in the system
event log. In addition, the controller is automatically reset,
restoring the network connection. To eliminate the potential
for the hang ensure that RxIntDelay is set to 0.
RxAbsIntDelay
-------------
(This parameter is supported only on 82540, 82545 and later adapters.)
Valid Range: 0-65535 (0=off)
Default Value: 128
This value, in units of 1.024 microseconds, limits the delay in which a
receive interrupt is generated. Useful only if RxIntDelay is non-zero,
this value ensures that an interrupt is generated after the initial
packet is received within the set amount of time. Proper tuning,
along with RxIntDelay, may improve traffic throughput in specific network
conditions.
Speed
-----
(This parameter is supported only on adapters with copper connections.)
Valid Settings: 0, 10, 100, 1000
Default Value: 0 (auto-negotiate at all supported speeds)
Speed forces the line speed to the specified value in megabits per second
(Mbps). If this parameter is not specified or is set to 0 and the link
partner is set to auto-negotiate, the board will auto-detect the correct
speed. Duplex should also be set when Speed is set to either 10 or 100.
TxDescriptors
-------------
Valid Range: 80-256 for 82542 and 82543-based adapters
80-4096 for all other supported adapters
Default Value: 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.
NOTE: Depending on the available system resources, the request for a
higher number of transmit descriptors may be denied. In this case,
use a lower number.
TxIntDelay
----------
Valid Range: 0-65535 (0=off)
Default Value: 64
This value delays the generation of transmit interrupts in units of
1.024 microseconds. Transmit interrupt reduction can improve CPU
efficiency if properly tuned for specific network traffic. If the
system is reporting dropped transmits, this value may be set too high
causing the driver to run out of available transmit descriptors.
TxAbsIntDelay
-------------
(This parameter is supported only on 82540, 82545 and later adapters.)
Valid Range: 0-65535 (0=off)
Default Value: 64
This value, in units of 1.024 microseconds, limits the delay in which a
transmit interrupt is generated. Useful only if TxIntDelay is non-zero,
this value ensures that an interrupt is generated after the initial
packet is sent on the wire within the set amount of time. Proper tuning,
along with TxIntDelay, may improve traffic throughput in specific
network conditions.
XsumRX
------
(This parameter is NOT supported on the 82542-based adapter.)
Valid Range: 0-1
Default Value: 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.
Speed and Duplex Configuration
==============================
Three keywords are used to control the speed and duplex configuration.
These keywords are Speed, Duplex, and AutoNeg.
If the board uses a fiber interface, these keywords are ignored, and the
fiber interface board only links at 1000 Mbps full-duplex.
For copper-based boards, the keywords interact as follows:
The default operation is auto-negotiate. The board advertises all
supported speed and duplex combinations, and it links at the highest
common speed and duplex mode IF the link partner is set to auto-negotiate.
If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps
is advertised (The 1000BaseT spec requires auto-negotiation.)
If Speed = 10 or 100, then both Speed and Duplex should be set. Auto-
negotiation is disabled, and the AutoNeg parameter is ignored. Partner
SHOULD also be forced.
The AutoNeg parameter is used when more control is required over the
auto-negotiation process. It should be used when you wish to control which
speed and duplex combinations are advertised during the auto-negotiation
process.
The parameter may be specified as either a decimal or hexadecimal value as
determined by the bitmap below.
Bit position 7 6 5 4 3 2 1 0
Decimal Value 128 64 32 16 8 4 2 1
Hex value 80 40 20 10 8 4 2 1
Speed (Mbps) N/A N/A 1000 N/A 100 100 10 10
Duplex Full Full Half Full Half
Some examples of using AutoNeg:
modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half)
modprobe e1000 AutoNeg=1 (Same as above)
modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full)
modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full)
modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half)
modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100
Half)
modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full)
modprobe e1000 AutoNeg=32 (Same as above)
Note that when this parameter is used, Speed and Duplex must not be specified.
If the link partner is forced to a specific speed and duplex, then this
parameter should not be used. Instead, use the Speed and Duplex parameters
previously mentioned to force the adapter to the same speed and duplex.
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 or /etc/modprobe.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(R) PRO/1000 Family of Adapters is e1000.
As an example, if you install the e1000 driver for two PRO/1000 adapters
(eth0 and eth1) and set the speed and duplex to 10full and 100half, add
the following to modules.conf or or modprobe.conf:
alias eth0 e1000
alias eth1 e1000
options e1000 Speed=10,100 Duplex=2,1
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
------------
Jumbo Frames support is enabled by changing the MTU to a value larger than
the default of 1500. Use the ifconfig command to increase the MTU size.
For example:
ifconfig eth<x> mtu 9000 up
This setting is not saved across reboots. It can be made permanent if
you add:
MTU=9000
to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>. This example
applies to the Red Hat distributions; other distributions may store this
setting in a different location.
Notes:
- To enable Jumbo Frames, increase the MTU size on the interface beyond
1500.
- The maximum MTU setting for Jumbo Frames is 16110. This value coincides
with the maximum Jumbo Frames size of 16128.
- Using Jumbo Frames at 10 or 100 Mbps may result in poor performance or
loss of link.
- Some Intel gigabit adapters that support Jumbo Frames have a frame size
limit of 9238 bytes, with a corresponding MTU size limit of 9216 bytes.
The adapters with this limitation are based on the Intel(R) 82571EB,
82572EI, 82573L and 80003ES2LAN controller. These correspond to the
following product names:
Intel(R) PRO/1000 PT Server Adapter
Intel(R) PRO/1000 PT Desktop Adapter
Intel(R) PRO/1000 PT Network Connection
Intel(R) PRO/1000 PT Dual Port Server Adapter
Intel(R) PRO/1000 PT Dual Port Network Connection
Intel(R) PRO/1000 PF Server Adapter
Intel(R) PRO/1000 PF Network Connection
Intel(R) PRO/1000 PF Dual Port Server Adapter
Intel(R) PRO/1000 PB Server Connection
Intel(R) PRO/1000 PL Network Connection
Intel(R) PRO/1000 EB Network Connection with I/O Acceleration
Intel(R) PRO/1000 EB Backplane Connection with I/O Acceleration
Intel(R) PRO/1000 PT Quad Port Server Adapter
- Adapters based on the Intel(R) 82542 and 82573V/E controller do not
support Jumbo Frames. These correspond to the following product names:
Intel(R) PRO/1000 Gigabit Server Adapter
Intel(R) PRO/1000 PM Network Connection
- The following adapters do not support Jumbo Frames:
Intel(R) 82562V 10/100 Network Connection
Intel(R) 82566DM Gigabit Network Connection
Intel(R) 82566DC Gigabit Network Connection
Intel(R) 82566MM Gigabit Network Connection
Intel(R) 82566MC Gigabit Network Connection
Intel(R) 82562GT 10/100 Network Connection
Intel(R) 82562G 10/100 Network Connection
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://sourceforge.net/projects/gkernel.
NOTE: Ethtool 1.6 only supports a limited set of ethtool options. Support
for a more complete ethtool feature set can be enabled by upgrading
ethtool to ethtool-1.8.1.
Enabling Wake on LAN* (WoL)
---------------------------
WoL is configured through the Ethtool* utility. Ethtool is included with
all versions of Red Hat after Red Hat 7.2. For other Linux distributions,
download and install Ethtool from the following website:
http://sourceforge.net/projects/gkernel.
For instructions on enabling WoL with Ethtool, refer to the website listed
above.
WoL will be enabled on the system during the next shut down or reboot.
For this driver version, in order to enable WoL, the e1000 driver must be
loaded when shutting down or rebooting the system.
Wake On LAN is only supported on port A for the following devices:
Intel(R) PRO/1000 PT Dual Port Network Connection
Intel(R) PRO/1000 PT Dual Port Server Connection
Intel(R) PRO/1000 PT Dual Port Server Adapter
Intel(R) PRO/1000 PF Dual Port Server Adapter
Intel(R) PRO/1000 PT Quad Port Server Adapter
NAPI
----
NAPI (Rx polling mode) is enabled in the e1000 driver.
See www.cyberus.ca/~hadi/usenix-paper.tgz for more information on NAPI.
Known Issues
============
Dropped Receive Packets on Half-duplex 10/100 Networks
------------------------------------------------------
If you have an Intel PCI Express adapter running at 10mbps or 100mbps, half-
duplex, you may observe occasional dropped receive packets. There are no
workarounds for this problem in this network configuration. The network must
be updated to operate in full-duplex, and/or 1000mbps only.
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.
Jumbo Frames on Foundry BigIron 8000 switch
-------------------------------------------
There is a known issue using Jumbo frames when connected to a Foundry
BigIron 8000 switch. This is a 3rd party limitation. If you experience
loss of packets, lower the MTU size.
Allocating Rx Buffers when Using Jumbo Frames
---------------------------------------------
Allocating Rx buffers when using Jumbo Frames on 2.6.x kernels may fail if
the available memory is heavily fragmented. This issue may be seen with PCI-X
adapters or with packet split disabled. This can be reduced or eliminated
by changing the amount of available memory for receive buffer allocation, by
increasing /proc/sys/vm/min_free_kbytes.
Multiple Interfaces on Same Ethernet Broadcast Network
------------------------------------------------------
Due to the default 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),
NOTE: This setting is not saved across reboots. The configuration
change can be made permanent by adding the line:
net.ipv4.conf.all.arp_filter = 1
to the file /etc/sysctl.conf
or,
install the interfaces in separate broadcast domains (either in
different switches or in a switch partitioned to VLANs).
82541/82547 can't link or are slow to link with some link partners
-----------------------------------------------------------------
There is a known compatibility issue with 82541/82547 and some
low-end switches where the link will not be established, or will
be slow to establish. In particular, these switches are known to
be incompatible with 82541/82547:
Planex FXG-08TE
I-O Data ETG-SH8
To workaround this issue, the driver can be compiled with an override
of the PHY's master/slave setting. Forcing master or forcing slave
mode will improve time-to-link.
# make CFLAGS_EXTRA=-DE1000_MASTER_SLAVE=<n>
Where <n> is:
0 = Hardware default
1 = Master mode
2 = Slave mode
3 = Auto master/slave
Disable rx flow control with ethtool
------------------------------------
In order to disable receive flow control using ethtool, you must turn
off auto-negotiation on the same command line.
For example:
ethtool -A eth? autoneg off rx off
Unplugging network cable while ethtool -p is running
----------------------------------------------------
In kernel versions 2.5.50 and later (including 2.6 kernel), unplugging
the network cable while ethtool -p is running will cause the system to
become unresponsive to keyboard commands, except for control-alt-delete.
Restarting the system appears to be the only remedy.
Support
=======
For general information, go to the Intel support website at:
http://support.intel.com
or the Intel Wired Networking project hosted by Sourceforge at:
http://sourceforge.net/projects/e1000
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 e1000-devel@lists.sf.net
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