384 lines
15 KiB
ReStructuredText
384 lines
15 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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======================================================
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Linux* Driver for Intel(R) Ethernet Network Connection
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======================================================
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Intel Gigabit Linux driver.
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Copyright(c) 2008-2018 Intel Corporation.
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Contents
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========
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- Identifying Your Adapter
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- Command Line Parameters
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- Additional Configurations
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- Support
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Identifying Your Adapter
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========================
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For information on how to identify your adapter, and for the latest Intel
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network drivers, refer to the Intel Support website:
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https://www.intel.com/support
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Command Line Parameters
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=======================
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If the driver is built as a module, the following optional parameters are used
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by entering them on the command line with the modprobe command using this
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syntax::
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modprobe e1000e [<option>=<VAL1>,<VAL2>,...]
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There needs to be a <VAL#> for each network port in the system supported by
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this driver. The values will be applied to each instance, in function order.
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For example::
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modprobe e1000e InterruptThrottleRate=16000,16000
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In this case, there are two network ports supported by e1000e in the system.
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The default value for each parameter is generally the recommended setting,
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unless otherwise noted.
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NOTE: A descriptor describes a data buffer and attributes related to the data
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buffer. This information is accessed by the hardware.
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InterruptThrottleRate
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---------------------
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:Valid Range: 0,1,3,4,100-100000
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:Default Value: 3
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Interrupt Throttle Rate controls the number of interrupts each interrupt
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vector can generate per second. Increasing ITR lowers latency at the cost of
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increased CPU utilization, though it may help throughput in some circumstances.
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Setting InterruptThrottleRate to a value greater or equal to 100
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will program the adapter to send out a maximum of that many interrupts
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per second, even if more packets have come in. This reduces interrupt
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load on the system and can lower CPU utilization under heavy load,
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but will increase latency as packets are not processed as quickly.
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The default behaviour of the driver previously assumed a static
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InterruptThrottleRate value of 8000, providing a good fallback value for
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all traffic types, but lacking in small packet performance and latency.
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The hardware can handle many more small packets per second however, and
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for this reason an adaptive interrupt moderation algorithm was implemented.
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The driver has two adaptive modes (setting 1 or 3) in which
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it dynamically adjusts the InterruptThrottleRate value based on the traffic
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that it receives. After determining the type of incoming traffic in the last
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timeframe, it will adjust the InterruptThrottleRate to an appropriate value
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for that traffic.
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The algorithm classifies the incoming traffic every interval into
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classes. Once the class is determined, the InterruptThrottleRate value is
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adjusted to suit that traffic type the best. There are three classes defined:
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"Bulk traffic", for large amounts of packets of normal size; "Low latency",
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for small amounts of traffic and/or a significant percentage of small
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packets; and "Lowest latency", for almost completely small packets or
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minimal traffic.
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- 0: Off
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Turns off any interrupt moderation and may improve small packet latency.
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However, this is generally not suitable for bulk throughput traffic due
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to the increased CPU utilization of the higher interrupt rate.
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- 1: Dynamic mode
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This mode attempts to moderate interrupts per vector while maintaining
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very low latency. This can sometimes cause extra CPU utilization. If
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planning on deploying e1000e in a latency sensitive environment, this
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parameter should be considered.
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- 3: Dynamic Conservative mode (default)
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In dynamic conservative mode, the InterruptThrottleRate value is set to
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4000 for traffic that falls in class "Bulk traffic". If traffic falls in
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the "Low latency" or "Lowest latency" class, the InterruptThrottleRate is
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increased stepwise to 20000. This default mode is suitable for most
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applications.
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- 4: Simplified Balancing mode
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In simplified mode the interrupt rate is based on the ratio of TX and
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RX traffic. If the bytes per second rate is approximately equal, the
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interrupt rate will drop as low as 2000 interrupts per second. If the
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traffic is mostly transmit or mostly receive, the interrupt rate could
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be as high as 8000.
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- 100-100000:
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Setting InterruptThrottleRate to a value greater or equal to 100
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will program the adapter to send at most that many interrupts per second,
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even if more packets have come in. This reduces interrupt load on the
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system and can lower CPU utilization under heavy load, but will increase
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latency as packets are not processed as quickly.
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NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and
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RxAbsIntDelay parameters. In other words, minimizing the receive and/or
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transmit absolute delays does not force the controller to generate more
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interrupts than what the Interrupt Throttle Rate allows.
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RxIntDelay
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----------
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:Valid Range: 0-65535 (0=off)
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:Default Value: 0
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This value delays the generation of receive interrupts in units of 1.024
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microseconds. Receive interrupt reduction can improve CPU efficiency if
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properly tuned for specific network traffic. Increasing this value adds extra
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latency to frame reception and can end up decreasing the throughput of TCP
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traffic. If the system is reporting dropped receives, this value may be set
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too high, causing the driver to run out of available receive descriptors.
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CAUTION: When setting RxIntDelay to a value other than 0, adapters may hang
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(stop transmitting) under certain network conditions. If this occurs a NETDEV
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WATCHDOG message is logged in the system event log. In addition, the
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controller is automatically reset, restoring the network connection. To
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eliminate the potential for the hang ensure that RxIntDelay is set to 0.
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RxAbsIntDelay
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-------------
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:Valid Range: 0-65535 (0=off)
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:Default Value: 8
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This value, in units of 1.024 microseconds, limits the delay in which a
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receive interrupt is generated. This value ensures that an interrupt is
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generated after the initial packet is received within the set amount of time,
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which is useful only if RxIntDelay is non-zero. Proper tuning, along with
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RxIntDelay, may improve traffic throughput in specific network conditions.
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TxIntDelay
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----------
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:Valid Range: 0-65535 (0=off)
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:Default Value: 8
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This value delays the generation of transmit interrupts in units of 1.024
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microseconds. Transmit interrupt reduction can improve CPU efficiency if
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properly tuned for specific network traffic. If the system is reporting
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dropped transmits, this value may be set too high causing the driver to run
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out of available transmit descriptors.
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TxAbsIntDelay
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-------------
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:Valid Range: 0-65535 (0=off)
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:Default Value: 32
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This value, in units of 1.024 microseconds, limits the delay in which a
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transmit interrupt is generated. It is useful only if TxIntDelay is non-zero.
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It ensures that an interrupt is generated after the initial Packet is sent on
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the wire within the set amount of time. Proper tuning, along with TxIntDelay,
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may improve traffic throughput in specific network conditions.
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copybreak
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---------
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:Valid Range: 0-xxxxxxx (0=off)
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:Default Value: 256
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The driver copies all packets below or equaling this size to a fresh receive
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buffer before handing it up the stack.
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This parameter differs from other parameters because it is a single (not 1,1,1
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etc.) parameter applied to all driver instances and it is also available
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during runtime at /sys/module/e1000e/parameters/copybreak.
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To use copybreak, type::
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modprobe e1000e.ko copybreak=128
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SmartPowerDownEnable
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--------------------
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:Valid Range: 0,1
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:Default Value: 0 (disabled)
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Allows the PHY to turn off in lower power states. The user can turn off this
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parameter in supported chipsets.
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KumeranLockLoss
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---------------
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:Valid Range: 0,1
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:Default Value: 1 (enabled)
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This workaround skips resetting the PHY at shutdown for the initial silicon
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releases of ICH8 systems.
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IntMode
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-------
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:Valid Range: 0-2
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:Default Value: 0
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+-------+----------------+
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| Value | Interrupt Mode |
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+=======+================+
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| 0 | Legacy |
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+-------+----------------+
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| 1 | MSI |
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+-------+----------------+
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| 2 | MSI-X |
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+-------+----------------+
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IntMode allows load time control over the type of interrupt registered for by
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the driver. MSI-X is required for multiple queue support, and some kernels and
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combinations of kernel .config options will force a lower level of interrupt
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support.
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This command will show different values for each type of interrupt::
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cat /proc/interrupts
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CrcStripping
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------------
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:Valid Range: 0,1
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:Default Value: 1 (enabled)
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Strip the CRC from received packets before sending up the network stack. If
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you have a machine with a BMC enabled but cannot receive IPMI traffic after
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loading or enabling the driver, try disabling this feature.
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WriteProtectNVM
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---------------
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:Valid Range: 0,1
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:Default Value: 1 (enabled)
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If set to 1, configure the hardware to ignore all write/erase cycles to the
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GbE region in the ICHx NVM (in order to prevent accidental corruption of the
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NVM). This feature can be disabled by setting the parameter to 0 during initial
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driver load.
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NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
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via setting the parameter to zero. Once the NVM has been locked (via the
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parameter at 1 when the driver loads) it cannot be unlocked except via power
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cycle.
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Debug
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-----
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:Valid Range: 0-16 (0=none,...,16=all)
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:Default Value: 0
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This parameter adjusts the level of debug messages displayed in the system logs.
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Additional Features and Configurations
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======================================
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Jumbo Frames
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------------
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Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU)
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to a value larger than the default value of 1500.
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Use the ifconfig command to increase the MTU size. For example, enter the
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following where <x> is the interface number::
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ifconfig eth<x> mtu 9000 up
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Alternatively, you can use the ip command as follows::
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ip link set mtu 9000 dev eth<x>
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ip link set up dev eth<x>
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This setting is not saved across reboots. The setting change can be made
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permanent by adding 'MTU=9000' to the file:
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- For RHEL: /etc/sysconfig/network-scripts/ifcfg-eth<x>
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- For SLES: /etc/sysconfig/network/<config_file>
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NOTE: The maximum MTU setting for Jumbo Frames is 8996. This value coincides
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with the maximum Jumbo Frames size of 9018 bytes.
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NOTE: Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
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poor performance or loss of link.
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NOTE: The following adapters limit Jumbo Frames sized packets to a maximum of
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4088 bytes:
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- Intel(R) 82578DM Gigabit Network Connection
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- Intel(R) 82577LM Gigabit Network Connection
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The following adapters do not support Jumbo Frames:
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- Intel(R) PRO/1000 Gigabit Server Adapter
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- Intel(R) PRO/1000 PM Network Connection
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- Intel(R) 82562G 10/100 Network Connection
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- Intel(R) 82562G-2 10/100 Network Connection
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- Intel(R) 82562GT 10/100 Network Connection
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- Intel(R) 82562GT-2 10/100 Network Connection
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- Intel(R) 82562V 10/100 Network Connection
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- Intel(R) 82562V-2 10/100 Network Connection
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- Intel(R) 82566DC Gigabit Network Connection
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- Intel(R) 82566DC-2 Gigabit Network Connection
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- Intel(R) 82566DM Gigabit Network Connection
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- Intel(R) 82566MC Gigabit Network Connection
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- Intel(R) 82566MM Gigabit Network Connection
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- Intel(R) 82567V-3 Gigabit Network Connection
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- Intel(R) 82577LC Gigabit Network Connection
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- Intel(R) 82578DC Gigabit Network Connection
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NOTE: Jumbo Frames cannot be configured on an 82579-based Network device if
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MACSec is enabled on the system.
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ethtool
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-------
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The driver utilizes the ethtool interface for driver configuration and
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diagnostics, as well as displaying statistical information. The latest ethtool
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version is required for this functionality. Download it at:
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https://www.kernel.org/pub/software/network/ethtool/
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NOTE: When validating enable/disable tests on some parts (for example, 82578),
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it is necessary to add a few seconds between tests when working with ethtool.
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Speed and Duplex Configuration
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------------------------------
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In addressing speed and duplex configuration issues, you need to distinguish
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between copper-based adapters and fiber-based adapters.
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In the default mode, an Intel(R) Ethernet Network Adapter using copper
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connections will attempt to auto-negotiate with its link partner to determine
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the best setting. If the adapter cannot establish link with the link partner
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using auto-negotiation, you may need to manually configure the adapter and link
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partner to identical settings to establish link and pass packets. This should
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only be needed when attempting to link with an older switch that does not
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support auto-negotiation or one that has been forced to a specific speed or
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duplex mode. Your link partner must match the setting you choose. 1 Gbps speeds
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and higher cannot be forced. Use the autonegotiation advertising setting to
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manually set devices for 1 Gbps and higher.
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Speed, duplex, and autonegotiation advertising are configured through the
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ethtool* utility.
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Caution: Only experienced network administrators should force speed and duplex
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or change autonegotiation advertising manually. The settings at the switch must
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always match the adapter settings. Adapter performance may suffer or your
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adapter may not operate if you configure the adapter differently from your
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switch.
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An Intel(R) Ethernet Network Adapter using fiber-based connections, however,
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will not attempt to auto-negotiate with its link partner since those adapters
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operate only in full duplex and only at their native speed.
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Enabling Wake on LAN* (WoL)
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---------------------------
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WoL is configured through the ethtool* utility.
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WoL will be enabled on the system during the next shut down or reboot. For
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this driver version, in order to enable WoL, the e1000e driver must be loaded
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prior to shutting down or suspending the system.
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NOTE: Wake on LAN is only supported on port A for the following devices:
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- Intel(R) PRO/1000 PT Dual Port Network Connection
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- Intel(R) PRO/1000 PT Dual Port Server Connection
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- Intel(R) PRO/1000 PT Dual Port Server Adapter
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- Intel(R) PRO/1000 PF Dual Port Server Adapter
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- Intel(R) PRO/1000 PT Quad Port Server Adapter
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- Intel(R) Gigabit PT Quad Port Server ExpressModule
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Support
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=======
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For general information, go to the Intel support website at:
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https://www.intel.com/support/
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or the Intel Wired Networking project hosted by Sourceforge at:
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https://sourceforge.net/projects/e1000
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If an issue is identified with the released source code on a supported kernel
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with a supported adapter, email the specific information related to the issue
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to e1000-devel@lists.sf.net.
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