Documentation/networking/device_drivers/ethernet/intel/e1000e.rst

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Documentation/networking/device_drivers/ethernet/intel/e1000e.rst
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.. SPDX-License-Identifier: GPL-2.0+

=====================================================
Linux Driver for Intel(R) Ethernet Network Connection
=====================================================

Intel Gigabit Linux driver.
Copyright(c) 2008-2018 Intel Corporation.

Contents
========

- Identifying Your Adapter
- Command Line Parameters
- Additional Configurations
- Support


Identifying Your Adapter
========================
For information on how to identify your adapter, and for the latest Intel
network drivers, refer to the Intel Support website:
https://www.intel.com/support


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 e1000e [<option>=<VAL1>,<VAL2>,...]

There needs to be a <VAL#> for each network port in the system supported by
this driver. The values will be applied to each instance, in function order.
For example::

    modprobe e1000e InterruptThrottleRate=16000,16000

In this case, there are two network ports supported by e1000e in the system.
The default value for each parameter is generally the recommended setting,
unless otherwise noted.

NOTE: A descriptor describes a data buffer and attributes related to the data
buffer. This information is accessed by the hardware.

InterruptThrottleRate
---------------------
:Valid Range: 0,1,3,4,100-100000
:Default Value: 3

Interrupt Throttle Rate controls the number of interrupts each interrupt
vector can generate per second. Increasing ITR lowers latency at the cost of
increased CPU utilization, though it may help throughput in some circumstances.

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.

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

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Implementation Notes