path: root/Documentation
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authorJeff Kirsher <jeffrey.t.kirsher@intel.com>2010-10-05 01:17:27 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-05 13:28:07 -0700
commitda8c01c4502adc1e7209a14626d583de7ca452fd (patch)
tree2c45408efe4607300c8c9f87f29335cf359e9684 /Documentation
parent2bff89c3f340776398bfaf6c94404ffcd09f6e77 (diff)
e1000e.txt: Add e1000e documentation
Adds documentation for the e1000e networking driver. Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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+Linux* Driver for Intel(R) Network Connection
+Intel Gigabit Linux driver.
+Copyright(c) 1999 - 2010 Intel Corporation.
+- Identifying Your Adapter
+- Command Line Parameters
+- Additional Configurations
+- Support
+Identifying Your Adapter
+The e1000e driver supports all PCI Express Intel(R) Gigabit Network
+Connections, except those that are 82575, 82576 and 82580-based*.
+* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
+ the e1000 driver, not the e1000e driver due to the 82546 part being used
+ behind a PCI Express bridge.
+For more information on how to identify your adapter, go to the Adapter &
+Driver ID Guide at:
+ http://support.intel.com/support/go/network/adapter/idguide.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://support.intel.com/support/go/network/adapter/home.htm
+Command Line Parameters
+The default value for each parameter is generally the recommended setting,
+unless otherwise noted.
+NOTES: 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
+Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
+ 4=simplified balancing)
+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 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".
+In simplified mode the interrupt rate is based on the ratio of Tx and
+Rx traffic. If the bytes per second rate is approximately equal the
+interrupt rate will drop as low as 2000 interrupts per second. If the
+traffic is mostly transmit or mostly receive, the interrupt rate could
+be as high as 8000.
+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.
+NOTE: When e1000e 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 e1000e 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.
+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
+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.
+Valid Range: 0-65535 (0=off)
+Default Value: 8
+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
+Valid Range: 0-65535 (0=off)
+Default Value: 8
+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.
+Valid Range: 0-65535 (0=off)
+Default Value: 32
+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.
+Valid Range: 0-xxxxxxx (0=off)
+Default Value: 256
+Driver copies all packets below or equaling this size to a fresh Rx
+buffer before handing it up the stack.
+This parameter is different than other parameters, in that it is a
+single (not 1,1,1 etc.) parameter applied to all driver instances and
+it is also available during runtime at
+Valid Range: 0-1
+Default Value: 0 (disabled)
+Allows PHY to turn off in lower power states. The user can set this parameter
+in supported chipsets.
+Valid Range: 0-1
+Default Value: 1 (enabled)
+This workaround skips resetting the PHY at shutdown for the initial
+silicon releases of ICH8 systems.
+Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
+Default Value: 2
+Allows changing the interrupt mode at module load time, without requiring a
+recompile. If the driver load fails to enable a specific interrupt mode, the
+driver will try other interrupt modes, from least to most compatible. The
+interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1)
+interrupts, only MSI and Legacy will be attempted.
+Valid Range: 0-1
+Default Value: 1 (enabled)
+Strip the CRC from received packets before sending up the network stack. If
+you have a machine with a BMC enabled but cannot receive IPMI traffic after
+loading or enabling the driver, try disabling this feature.
+Valid Range: 0-1
+Default Value: 1 (enabled)
+Set the hardware to ignore all write/erase cycles to the GbE region in the
+ICHx NVM (non-volatile memory). This feature can be disabled by the
+WriteProtectNVM module parameter (enabled by default) only after a hardware
+reset, but the machine must be power cycled before trying to enable writes.
+Note: the kernel boot option iomem=relaxed may need to be set if the kernel
+config option CONFIG_STRICT_DEVMEM=y, if the root user wants to write the
+NVM from user space via ethtool.
+Additional Configurations
+ 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.
+ Notes:
+ - The maximum MTU setting for Jumbo Frames is 9216. This value coincides
+ with the maximum Jumbo Frames size of 9234 bytes.
+ - Using Jumbo Frames at 10 or 100 Mbps is not supported and may result in
+ poor performance or loss of link.
+ - Some adapters limit Jumbo Frames sized packets to a maximum of
+ 4096 bytes and some adapters do not support Jumbo Frames.
+ Ethtool
+ -------
+ The driver utilizes the ethtool interface for driver configuration and
+ diagnostics, as well as displaying statistical information. We
+ strongly recommend downloading the latest version of Ethtool at:
+ http://sourceforge.net/projects/gkernel.
+ Speed and Duplex
+ ----------------
+ Speed and Duplex are configured through the Ethtool* utility. For
+ instructions, refer to the Ethtool man page.
+ Enabling Wake on LAN* (WoL)
+ ---------------------------
+ WoL is configured through the Ethtool* utility. For instructions on
+ enabling WoL with Ethtool, refer to the Ethtool man page.
+ WoL will be enabled on the system during the next shut down or reboot.
+ For this driver version, in order to enable WoL, the e1000e driver must be
+ loaded when shutting down or rebooting the system.
+ In most cases Wake On LAN is only supported on port A for multiple port
+ adapters. To verify if a port supports Wake on LAN run ethtool eth<X>.
+For general information, go to the Intel support website at:
+ www.intel.com/support/
+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