Documentation/networking/e1000e.txt: Update documentation

Linux* Driver for Intel(R) Network Connection

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Intel Gigabit Linux driver.

Copyright(c) 1999 - 2010 Intel Corporation.

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.

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

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

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.

Valid Range:   0-xxxxxxx (0=off)

Default Value: 256

Driver copies all packets below or equaling this size to a fresh Rx

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

WriteProtectNVM

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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.

Valid Range: 0,1

Default Value: 1

If set to 1, configure the hardware to ignore all write/erase cycles to the

GbE region in the ICHx NVM (in order to prevent accidental corruption of the

NVM). This feature can be disabled by setting the parameter to 0 during initial

driver load.

NOTE: The machine must be power cycled (full off/on) when enabling NVM writes

via setting the parameter to zero. Once the NVM has been locked (via the

parameter at 1 when the driver loads) it cannot be unlocked except via power

cycle.

Additional Configurations

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  - Some adapters limit Jumbo Frames sized packets to a maximum of

    4096 bytes and some adapters do not support Jumbo Frames.

  Ethtool

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  The driver utilizes the ethtool interface for driver configuration and

  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>.

  adapters. To verify if a port supports Wake on Lan run Ethtool eth<X>.

Support

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