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Documentation / networking / e1000e.txt

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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 EST.

1	Linux* Driver for Intel(R) Ethernet Network Connection
2	======================================================
4	Intel Gigabit Linux driver.
5	Copyright(c) 1999 - 2013 Intel Corporation.
7	Contents
8	========
10	- Identifying Your Adapter
11	- Command Line Parameters
12	- Additional Configurations
13	- Support
15	Identifying Your Adapter
16	========================
18	The e1000e driver supports all PCI Express Intel(R) Gigabit Network
19	Connections, except those that are 82575, 82576 and 82580-based*.
21	* NOTE: The Intel(R) PRO/1000 P Dual Port Server Adapter is supported by
22	  the e1000 driver, not the e1000e driver due to the 82546 part being used
23	  behind a PCI Express bridge.
25	For more information on how to identify your adapter, go to the Adapter &
26	Driver ID Guide at:
28	    http://support.intel.com/support/go/network/adapter/idguide.htm
30	For the latest Intel network drivers for Linux, refer to the following
31	website.  In the search field, enter your adapter name or type, or use the
32	networking link on the left to search for your adapter:
34	    http://support.intel.com/support/go/network/adapter/home.htm
36	Command Line Parameters
37	=======================
39	The default value for each parameter is generally the recommended setting,
40	unless otherwise noted.
42	NOTES:  For more information about the InterruptThrottleRate,
43	        RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay
44	        parameters, see the application note at:
45	        http://www.intel.com/design/network/applnots/ap450.htm
47	InterruptThrottleRate
48	---------------------
49	Valid Range:   0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative,
50	                                   4=simplified balancing)
51	Default Value: 3
53	The driver can limit the amount of interrupts per second that the adapter
54	will generate for incoming packets. It does this by writing a value to the
55	adapter that is based on the maximum amount of interrupts that the adapter
56	will generate per second.
58	Setting InterruptThrottleRate to a value greater or equal to 100
59	will program the adapter to send out a maximum of that many interrupts
60	per second, even if more packets have come in. This reduces interrupt
61	load on the system and can lower CPU utilization under heavy load,
62	but will increase latency as packets are not processed as quickly.
64	The default behaviour of the driver previously assumed a static
65	InterruptThrottleRate value of 8000, providing a good fallback value for
66	all traffic types, but lacking in small packet performance and latency.
67	The hardware can handle many more small packets per second however, and
68	for this reason an adaptive interrupt moderation algorithm was implemented.
70	The driver has two adaptive modes (setting 1 or 3) in which
71	it dynamically adjusts the InterruptThrottleRate value based on the traffic
72	that it receives. After determining the type of incoming traffic in the last
73	timeframe, it will adjust the InterruptThrottleRate to an appropriate value
74	for that traffic.
76	The algorithm classifies the incoming traffic every interval into
77	classes.  Once the class is determined, the InterruptThrottleRate value is
78	adjusted to suit that traffic type the best. There are three classes defined:
79	"Bulk traffic", for large amounts of packets of normal size; "Low latency",
80	for small amounts of traffic and/or a significant percentage of small
81	packets; and "Lowest latency", for almost completely small packets or
82	minimal traffic.
84	In dynamic conservative mode, the InterruptThrottleRate value is set to 4000
85	for traffic that falls in class "Bulk traffic". If traffic falls in the "Low
86	latency" or "Lowest latency" class, the InterruptThrottleRate is increased
87	stepwise to 20000. This default mode is suitable for most applications.
89	For situations where low latency is vital such as cluster or
90	grid computing, the algorithm can reduce latency even more when
91	InterruptThrottleRate is set to mode 1. In this mode, which operates
92	the same as mode 3, the InterruptThrottleRate will be increased stepwise to
93	70000 for traffic in class "Lowest latency".
95	In simplified mode the interrupt rate is based on the ratio of TX and
96	RX traffic.  If the bytes per second rate is approximately equal, the
97	interrupt rate will drop as low as 2000 interrupts per second.  If the
98	traffic is mostly transmit or mostly receive, the interrupt rate could
99	be as high as 8000.
101	Setting InterruptThrottleRate to 0 turns off any interrupt moderation
102	and may improve small packet latency, but is generally not suitable
103	for bulk throughput traffic.
105	NOTE:  InterruptThrottleRate takes precedence over the TxAbsIntDelay and
106	       RxAbsIntDelay parameters.  In other words, minimizing the receive
107	       and/or transmit absolute delays does not force the controller to
108	       generate more interrupts than what the Interrupt Throttle Rate
109	       allows.
111	NOTE:  When e1000e is loaded with default settings and multiple adapters
112	       are in use simultaneously, the CPU utilization may increase non-
113	       linearly.  In order to limit the CPU utilization without impacting
114	       the overall throughput, we recommend that you load the driver as
115	       follows:
117	           modprobe e1000e InterruptThrottleRate=3000,3000,3000
119	       This sets the InterruptThrottleRate to 3000 interrupts/sec for
120	       the first, second, and third instances of the driver.  The range
121	       of 2000 to 3000 interrupts per second works on a majority of
122	       systems and is a good starting point, but the optimal value will
123	       be platform-specific.  If CPU utilization is not a concern, use
124	       RX_POLLING (NAPI) and default driver settings.
126	RxIntDelay
127	----------
128	Valid Range:   0-65535 (0=off)
129	Default Value: 0
131	This value delays the generation of receive interrupts in units of 1.024
132	microseconds.  Receive interrupt reduction can improve CPU efficiency if
133	properly tuned for specific network traffic.  Increasing this value adds
134	extra latency to frame reception and can end up decreasing the throughput
135	of TCP traffic.  If the system is reporting dropped receives, this value
136	may be set too high, causing the driver to run out of available receive
137	descriptors.
139	CAUTION:  When setting RxIntDelay to a value other than 0, adapters may
140	          hang (stop transmitting) under certain network conditions.  If
141	          this occurs a NETDEV WATCHDOG message is logged in the system
142	          event log.  In addition, the controller is automatically reset,
143	          restoring the network connection.  To eliminate the potential
144	          for the hang ensure that RxIntDelay is set to 0.
146	RxAbsIntDelay
147	-------------
148	Valid Range:   0-65535 (0=off)
149	Default Value: 8
151	This value, in units of 1.024 microseconds, limits the delay in which a
152	receive interrupt is generated.  Useful only if RxIntDelay is non-zero,
153	this value ensures that an interrupt is generated after the initial
154	packet is received within the set amount of time.  Proper tuning,
155	along with RxIntDelay, may improve traffic throughput in specific network
156	conditions.
158	TxIntDelay
159	----------
160	Valid Range:   0-65535 (0=off)
161	Default Value: 8
163	This value delays the generation of transmit interrupts in units of
164	1.024 microseconds.  Transmit interrupt reduction can improve CPU
165	efficiency if properly tuned for specific network traffic.  If the
166	system is reporting dropped transmits, this value may be set too high
167	causing the driver to run out of available transmit descriptors.
169	TxAbsIntDelay
170	-------------
171	Valid Range:   0-65535 (0=off)
172	Default Value: 32
174	This value, in units of 1.024 microseconds, limits the delay in which a
175	transmit interrupt is generated.  Useful only if TxIntDelay is non-zero,
176	this value ensures that an interrupt is generated after the initial
177	packet is sent on the wire within the set amount of time.  Proper tuning,
178	along with TxIntDelay, may improve traffic throughput in specific
179	network conditions.
181	Copybreak
182	---------
183	Valid Range:   0-xxxxxxx (0=off)
184	Default Value: 256
186	Driver copies all packets below or equaling this size to a fresh RX
187	buffer before handing it up the stack.
189	This parameter is different than other parameters, in that it is a
190	single (not 1,1,1 etc.) parameter applied to all driver instances and
191	it is also available during runtime at
192	/sys/module/e1000e/parameters/copybreak
194	SmartPowerDownEnable
195	--------------------
196	Valid Range: 0-1
197	Default Value:  0 (disabled)
199	Allows PHY to turn off in lower power states. The user can set this parameter
200	in supported chipsets.
202	KumeranLockLoss
203	---------------
204	Valid Range: 0-1
205	Default Value: 1 (enabled)
207	This workaround skips resetting the PHY at shutdown for the initial
208	silicon releases of ICH8 systems.
210	IntMode
211	-------
212	Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X)
213	Default Value: 2
215	Allows changing the interrupt mode at module load time, without requiring a
216	recompile. If the driver load fails to enable a specific interrupt mode, the
217	driver will try other interrupt modes, from least to most compatible.  The
218	interrupt order is MSI-X, MSI, Legacy.  If specifying MSI (IntMode=1)
219	interrupts, only MSI and Legacy will be attempted.
221	CrcStripping
222	------------
223	Valid Range: 0-1
224	Default Value: 1 (enabled)
226	Strip the CRC from received packets before sending up the network stack.  If
227	you have a machine with a BMC enabled but cannot receive IPMI traffic after
228	loading or enabling the driver, try disabling this feature.
230	WriteProtectNVM
231	---------------
232	Valid Range: 0,1
233	Default Value: 1
235	If set to 1, configure the hardware to ignore all write/erase cycles to the
236	GbE region in the ICHx NVM (in order to prevent accidental corruption of the
237	NVM). This feature can be disabled by setting the parameter to 0 during initial
238	driver load.
239	NOTE: The machine must be power cycled (full off/on) when enabling NVM writes
240	via setting the parameter to zero. Once the NVM has been locked (via the
241	parameter at 1 when the driver loads) it cannot be unlocked except via power
242	cycle.
244	Additional Configurations
245	=========================
247	  Jumbo Frames
248	  ------------
249	  Jumbo Frames support is enabled by changing the MTU to a value larger than
250	  the default of 1500.  Use the ifconfig command to increase the MTU size.
251	  For example:
253	       ifconfig eth<x> mtu 9000 up
255	  This setting is not saved across reboots.
257	  Notes:
259	  - The maximum MTU setting for Jumbo Frames is 9216.  This value coincides
260	    with the maximum Jumbo Frames size of 9234 bytes.
262	  - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in
263	    poor performance or loss of link.
265	  - Some adapters limit Jumbo Frames sized packets to a maximum of
266	    4096 bytes and some adapters do not support Jumbo Frames.
268	  - Jumbo Frames cannot be configured on an 82579-based Network device, if
269	    MACSec is enabled on the system.
271	  ethtool
272	  -------
273	  The driver utilizes the ethtool interface for driver configuration and
274	  diagnostics, as well as displaying statistical information.  We
275	  strongly recommend downloading the latest version of ethtool at:
277	  http://ftp.kernel.org/pub/software/network/ethtool/
279	  NOTE: When validating enable/disable tests on some parts (82578, for example)
280	  you need to add a few seconds between tests when working with ethtool.
282	  Speed and Duplex
283	  ----------------
284	  Speed and Duplex are configured through the ethtool* utility. For
285	  instructions,  refer to the ethtool man page.
287	  Enabling Wake on LAN* (WoL)
288	  ---------------------------
289	  WoL is configured through the ethtool* utility. For instructions on
290	  enabling WoL with ethtool, refer to the ethtool man page.
292	  WoL will be enabled on the system during the next shut down or reboot.
293	  For this driver version, in order to enable WoL, the e1000e driver must be
294	  loaded when shutting down or rebooting the system.
296	  In most cases Wake On LAN is only supported on port A for multiple port
297	  adapters. To verify if a port supports Wake on Lan run ethtool eth<X>.
299	Support
300	=======
302	For general information, go to the Intel support website at:
304	    www.intel.com/support/
306	or the Intel Wired Networking project hosted by Sourceforge at:
308	    http://sourceforge.net/projects/e1000
310	If an issue is identified with the released source code on the supported
311	kernel with a supported adapter, email the specific information related
312	to the issue to e1000-devel@lists.sf.net
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