e1000.rst (17521B)
1.. SPDX-License-Identifier: GPL-2.0+ 2 3========================================================== 4Linux Base Driver for Intel(R) Ethernet Network Connection 5========================================================== 6 7Intel Gigabit Linux driver. 8Copyright(c) 1999 - 2013 Intel Corporation. 9 10Contents 11======== 12 13- Identifying Your Adapter 14- Command Line Parameters 15- Speed and Duplex Configuration 16- Additional Configurations 17- Support 18 19Identifying Your Adapter 20======================== 21 22For more information on how to identify your adapter, go to the Adapter & 23Driver ID Guide at: 24 25 http://support.intel.com/support/go/network/adapter/idguide.htm 26 27For the latest Intel network drivers for Linux, refer to the following 28website. In the search field, enter your adapter name or type, or use the 29networking link on the left to search for your adapter: 30 31 http://support.intel.com/support/go/network/adapter/home.htm 32 33Command Line Parameters 34======================= 35 36The default value for each parameter is generally the recommended setting, 37unless otherwise noted. 38 39NOTES: 40 For more information about the AutoNeg, Duplex, and Speed 41 parameters, see the "Speed and Duplex Configuration" section in 42 this document. 43 44 For more information about the InterruptThrottleRate, 45 RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay 46 parameters, see the application note at: 47 http://www.intel.com/design/network/applnots/ap450.htm 48 49AutoNeg 50------- 51 52(Supported only on adapters with copper connections) 53 54:Valid Range: 0x01-0x0F, 0x20-0x2F 55:Default Value: 0x2F 56 57This parameter is a bit-mask that specifies the speed and duplex settings 58advertised by the adapter. When this parameter is used, the Speed and 59Duplex parameters must not be specified. 60 61NOTE: 62 Refer to the Speed and Duplex section of this readme for more 63 information on the AutoNeg parameter. 64 65Duplex 66------ 67 68(Supported only on adapters with copper connections) 69 70:Valid Range: 0-2 (0=auto-negotiate, 1=half, 2=full) 71:Default Value: 0 72 73This defines the direction in which data is allowed to flow. Can be 74either one or two-directional. If both Duplex and the link partner are 75set to auto-negotiate, the board auto-detects the correct duplex. If the 76link partner is forced (either full or half), Duplex defaults to half- 77duplex. 78 79FlowControl 80----------- 81 82:Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx) 83:Default Value: Reads flow control settings from the EEPROM 84 85This parameter controls the automatic generation(Tx) and response(Rx) 86to Ethernet PAUSE frames. 87 88InterruptThrottleRate 89--------------------- 90 91(not supported on Intel(R) 82542, 82543 or 82544-based adapters) 92 93:Valid Range: 94 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative, 95 4=simplified balancing) 96:Default Value: 3 97 98The driver can limit the amount of interrupts per second that the adapter 99will generate for incoming packets. It does this by writing a value to the 100adapter that is based on the maximum amount of interrupts that the adapter 101will generate per second. 102 103Setting InterruptThrottleRate to a value greater or equal to 100 104will program the adapter to send out a maximum of that many interrupts 105per second, even if more packets have come in. This reduces interrupt 106load on the system and can lower CPU utilization under heavy load, 107but will increase latency as packets are not processed as quickly. 108 109The default behaviour of the driver previously assumed a static 110InterruptThrottleRate value of 8000, providing a good fallback value for 111all traffic types,but lacking in small packet performance and latency. 112The hardware can handle many more small packets per second however, and 113for this reason an adaptive interrupt moderation algorithm was implemented. 114 115Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which 116it dynamically adjusts the InterruptThrottleRate value based on the traffic 117that it receives. After determining the type of incoming traffic in the last 118timeframe, it will adjust the InterruptThrottleRate to an appropriate value 119for that traffic. 120 121The algorithm classifies the incoming traffic every interval into 122classes. Once the class is determined, the InterruptThrottleRate value is 123adjusted to suit that traffic type the best. There are three classes defined: 124"Bulk traffic", for large amounts of packets of normal size; "Low latency", 125for small amounts of traffic and/or a significant percentage of small 126packets; and "Lowest latency", for almost completely small packets or 127minimal traffic. 128 129In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 130for traffic that falls in class "Bulk traffic". If traffic falls in the "Low 131latency" or "Lowest latency" class, the InterruptThrottleRate is increased 132stepwise to 20000. This default mode is suitable for most applications. 133 134For situations where low latency is vital such as cluster or 135grid computing, the algorithm can reduce latency even more when 136InterruptThrottleRate is set to mode 1. In this mode, which operates 137the same as mode 3, the InterruptThrottleRate will be increased stepwise to 13870000 for traffic in class "Lowest latency". 139 140In simplified mode the interrupt rate is based on the ratio of TX and 141RX traffic. If the bytes per second rate is approximately equal, the 142interrupt rate will drop as low as 2000 interrupts per second. If the 143traffic is mostly transmit or mostly receive, the interrupt rate could 144be as high as 8000. 145 146Setting InterruptThrottleRate to 0 turns off any interrupt moderation 147and may improve small packet latency, but is generally not suitable 148for bulk throughput traffic. 149 150NOTE: 151 InterruptThrottleRate takes precedence over the TxAbsIntDelay and 152 RxAbsIntDelay parameters. In other words, minimizing the receive 153 and/or transmit absolute delays does not force the controller to 154 generate more interrupts than what the Interrupt Throttle Rate 155 allows. 156 157CAUTION: 158 If you are using the Intel(R) PRO/1000 CT Network Connection 159 (controller 82547), setting InterruptThrottleRate to a value 160 greater than 75,000, may hang (stop transmitting) adapters 161 under certain network conditions. If this occurs a NETDEV 162 WATCHDOG message is logged in the system event log. In 163 addition, the controller is automatically reset, restoring 164 the network connection. To eliminate the potential for the 165 hang, ensure that InterruptThrottleRate is set no greater 166 than 75,000 and is not set to 0. 167 168NOTE: 169 When e1000 is loaded with default settings and multiple adapters 170 are in use simultaneously, the CPU utilization may increase non- 171 linearly. In order to limit the CPU utilization without impacting 172 the overall throughput, we recommend that you load the driver as 173 follows:: 174 175 modprobe e1000 InterruptThrottleRate=3000,3000,3000 176 177 This sets the InterruptThrottleRate to 3000 interrupts/sec for 178 the first, second, and third instances of the driver. The range 179 of 2000 to 3000 interrupts per second works on a majority of 180 systems and is a good starting point, but the optimal value will 181 be platform-specific. If CPU utilization is not a concern, use 182 RX_POLLING (NAPI) and default driver settings. 183 184RxDescriptors 185------------- 186 187:Valid Range: 188 - 48-256 for 82542 and 82543-based adapters 189 - 48-4096 for all other supported adapters 190:Default Value: 256 191 192This value specifies the number of receive buffer descriptors allocated 193by the driver. Increasing this value allows the driver to buffer more 194incoming packets, at the expense of increased system memory utilization. 195 196Each descriptor is 16 bytes. A receive buffer is also allocated for each 197descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending 198on the MTU setting. The maximum MTU size is 16110. 199 200NOTE: 201 MTU designates the frame size. It only needs to be set for Jumbo 202 Frames. Depending on the available system resources, the request 203 for a higher number of receive descriptors may be denied. In this 204 case, use a lower number. 205 206RxIntDelay 207---------- 208 209:Valid Range: 0-65535 (0=off) 210:Default Value: 0 211 212This value delays the generation of receive interrupts in units of 1.024 213microseconds. Receive interrupt reduction can improve CPU efficiency if 214properly tuned for specific network traffic. Increasing this value adds 215extra latency to frame reception and can end up decreasing the throughput 216of TCP traffic. If the system is reporting dropped receives, this value 217may be set too high, causing the driver to run out of available receive 218descriptors. 219 220CAUTION: 221 When setting RxIntDelay to a value other than 0, adapters may 222 hang (stop transmitting) under certain network conditions. If 223 this occurs a NETDEV WATCHDOG message is logged in the system 224 event log. In addition, the controller is automatically reset, 225 restoring the network connection. To eliminate the potential 226 for the hang ensure that RxIntDelay is set to 0. 227 228RxAbsIntDelay 229------------- 230 231(This parameter is supported only on 82540, 82545 and later adapters.) 232 233:Valid Range: 0-65535 (0=off) 234:Default Value: 128 235 236This value, in units of 1.024 microseconds, limits the delay in which a 237receive interrupt is generated. Useful only if RxIntDelay is non-zero, 238this value ensures that an interrupt is generated after the initial 239packet is received within the set amount of time. Proper tuning, 240along with RxIntDelay, may improve traffic throughput in specific network 241conditions. 242 243Speed 244----- 245 246(This parameter is supported only on adapters with copper connections.) 247 248:Valid Settings: 0, 10, 100, 1000 249:Default Value: 0 (auto-negotiate at all supported speeds) 250 251Speed forces the line speed to the specified value in megabits per second 252(Mbps). If this parameter is not specified or is set to 0 and the link 253partner is set to auto-negotiate, the board will auto-detect the correct 254speed. Duplex should also be set when Speed is set to either 10 or 100. 255 256TxDescriptors 257------------- 258 259:Valid Range: 260 - 48-256 for 82542 and 82543-based adapters 261 - 48-4096 for all other supported adapters 262:Default Value: 256 263 264This value is the number of transmit descriptors allocated by the driver. 265Increasing this value allows the driver to queue more transmits. Each 266descriptor is 16 bytes. 267 268NOTE: 269 Depending on the available system resources, the request for a 270 higher number of transmit descriptors may be denied. In this case, 271 use a lower number. 272 273TxIntDelay 274---------- 275 276:Valid Range: 0-65535 (0=off) 277:Default Value: 8 278 279This value delays the generation of transmit interrupts in units of 2801.024 microseconds. Transmit interrupt reduction can improve CPU 281efficiency if properly tuned for specific network traffic. If the 282system is reporting dropped transmits, this value may be set too high 283causing the driver to run out of available transmit descriptors. 284 285TxAbsIntDelay 286------------- 287 288(This parameter is supported only on 82540, 82545 and later adapters.) 289 290:Valid Range: 0-65535 (0=off) 291:Default Value: 32 292 293This value, in units of 1.024 microseconds, limits the delay in which a 294transmit interrupt is generated. Useful only if TxIntDelay is non-zero, 295this value ensures that an interrupt is generated after the initial 296packet is sent on the wire within the set amount of time. Proper tuning, 297along with TxIntDelay, may improve traffic throughput in specific 298network conditions. 299 300XsumRX 301------ 302 303(This parameter is NOT supported on the 82542-based adapter.) 304 305:Valid Range: 0-1 306:Default Value: 1 307 308A value of '1' indicates that the driver should enable IP checksum 309offload for received packets (both UDP and TCP) to the adapter hardware. 310 311Copybreak 312--------- 313 314:Valid Range: 0-xxxxxxx (0=off) 315:Default Value: 256 316:Usage: modprobe e1000.ko copybreak=128 317 318Driver copies all packets below or equaling this size to a fresh RX 319buffer before handing it up the stack. 320 321This parameter is different than other parameters, in that it is a 322single (not 1,1,1 etc.) parameter applied to all driver instances and 323it is also available during runtime at 324/sys/module/e1000/parameters/copybreak 325 326SmartPowerDownEnable 327-------------------- 328 329:Valid Range: 0-1 330:Default Value: 0 (disabled) 331 332Allows PHY to turn off in lower power states. The user can turn off 333this parameter in supported chipsets. 334 335Speed and Duplex Configuration 336============================== 337 338Three keywords are used to control the speed and duplex configuration. 339These keywords are Speed, Duplex, and AutoNeg. 340 341If the board uses a fiber interface, these keywords are ignored, and the 342fiber interface board only links at 1000 Mbps full-duplex. 343 344For copper-based boards, the keywords interact as follows: 345 346- The default operation is auto-negotiate. The board advertises all 347 supported speed and duplex combinations, and it links at the highest 348 common speed and duplex mode IF the link partner is set to auto-negotiate. 349 350- If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps 351 is advertised (The 1000BaseT spec requires auto-negotiation.) 352 353- If Speed = 10 or 100, then both Speed and Duplex should be set. Auto- 354 negotiation is disabled, and the AutoNeg parameter is ignored. Partner 355 SHOULD also be forced. 356 357The AutoNeg parameter is used when more control is required over the 358auto-negotiation process. It should be used when you wish to control which 359speed and duplex combinations are advertised during the auto-negotiation 360process. 361 362The parameter may be specified as either a decimal or hexadecimal value as 363determined by the bitmap below. 364 365============== ====== ====== ======= ======= ====== ====== ======= ====== 366Bit position 7 6 5 4 3 2 1 0 367Decimal Value 128 64 32 16 8 4 2 1 368Hex value 80 40 20 10 8 4 2 1 369Speed (Mbps) N/A N/A 1000 N/A 100 100 10 10 370Duplex Full Full Half Full Half 371============== ====== ====== ======= ======= ====== ====== ======= ====== 372 373Some examples of using AutoNeg:: 374 375 modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half) 376 modprobe e1000 AutoNeg=1 (Same as above) 377 modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full) 378 modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full) 379 modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half) 380 modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100 381 Half) 382 modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full) 383 modprobe e1000 AutoNeg=32 (Same as above) 384 385Note that when this parameter is used, Speed and Duplex must not be specified. 386 387If the link partner is forced to a specific speed and duplex, then this 388parameter should not be used. Instead, use the Speed and Duplex parameters 389previously mentioned to force the adapter to the same speed and duplex. 390 391Additional Configurations 392========================= 393 394Jumbo Frames 395------------ 396 397 Jumbo Frames support is enabled by changing the MTU to a value larger than 398 the default of 1500. Use the ifconfig command to increase the MTU size. 399 For example:: 400 401 ifconfig eth<x> mtu 9000 up 402 403 This setting is not saved across reboots. It can be made permanent if 404 you add:: 405 406 MTU=9000 407 408 to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>. This example 409 applies to the Red Hat distributions; other distributions may store this 410 setting in a different location. 411 412Notes: 413 Degradation in throughput performance may be observed in some Jumbo frames 414 environments. If this is observed, increasing the application's socket buffer 415 size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help. 416 See the specific application manual and /usr/src/linux*/Documentation/ 417 networking/ip-sysctl.txt for more details. 418 419 - The maximum MTU setting for Jumbo Frames is 16110. This value coincides 420 with the maximum Jumbo Frames size of 16128. 421 422 - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in 423 poor performance or loss of link. 424 425 - Adapters based on the Intel(R) 82542 and 82573V/E controller do not 426 support Jumbo Frames. These correspond to the following product names:: 427 428 Intel(R) PRO/1000 Gigabit Server Adapter 429 Intel(R) PRO/1000 PM Network Connection 430 431ethtool 432------- 433 434 The driver utilizes the ethtool interface for driver configuration and 435 diagnostics, as well as displaying statistical information. The ethtool 436 version 1.6 or later is required for this functionality. 437 438 The latest release of ethtool can be found from 439 https://www.kernel.org/pub/software/network/ethtool/ 440 441Enabling Wake on LAN (WoL) 442-------------------------- 443 444 WoL is configured through the ethtool utility. 445 446 WoL will be enabled on the system during the next shut down or reboot. 447 For this driver version, in order to enable WoL, the e1000 driver must be 448 loaded when shutting down or rebooting the system. 449 450Support 451======= 452 453For general information, go to the Intel support website at: 454 455 http://support.intel.com 456 457or the Intel Wired Networking project hosted by Sourceforge at: 458 459 http://sourceforge.net/projects/e1000 460 461If an issue is identified with the released source code on the supported 462kernel with a supported adapter, email the specific information related 463to the issue to e1000-devel@lists.sf.net