1Linux* Base Driver for Intel(R) Ethernet Network Connection 2=========================================================== 3 4Intel Gigabit Linux driver. 5Copyright(c) 1999 - 2013 Intel Corporation. 6 7Contents 8======== 9 10- Identifying Your Adapter 11- Command Line Parameters 12- Speed and Duplex Configuration 13- Additional Configurations 14- Support 15 16Identifying Your Adapter 17======================== 18 19For more information on how to identify your adapter, go to the Adapter & 20Driver ID Guide at: 21 22 http://support.intel.com/support/go/network/adapter/idguide.htm 23 24For the latest Intel network drivers for Linux, refer to the following 25website. In the search field, enter your adapter name or type, or use the 26networking link on the left to search for your adapter: 27 28 http://support.intel.com/support/go/network/adapter/home.htm 29 30Command Line Parameters 31======================= 32 33The default value for each parameter is generally the recommended setting, 34unless otherwise noted. 35 36NOTES: For more information about the AutoNeg, Duplex, and Speed 37 parameters, see the "Speed and Duplex Configuration" section in 38 this document. 39 40 For more information about the InterruptThrottleRate, 41 RxIntDelay, TxIntDelay, RxAbsIntDelay, and TxAbsIntDelay 42 parameters, see the application note at: 43 http://www.intel.com/design/network/applnots/ap450.htm 44 45AutoNeg 46------- 47(Supported only on adapters with copper connections) 48Valid Range: 0x01-0x0F, 0x20-0x2F 49Default Value: 0x2F 50 51This parameter is a bit-mask that specifies the speed and duplex settings 52advertised by the adapter. When this parameter is used, the Speed and 53Duplex parameters must not be specified. 54 55NOTE: Refer to the Speed and Duplex section of this readme for more 56 information on the AutoNeg parameter. 57 58Duplex 59------ 60(Supported only on adapters with copper connections) 61Valid Range: 0-2 (0=auto-negotiate, 1=half, 2=full) 62Default Value: 0 63 64This defines the direction in which data is allowed to flow. Can be 65either one or two-directional. If both Duplex and the link partner are 66set to auto-negotiate, the board auto-detects the correct duplex. If the 67link partner is forced (either full or half), Duplex defaults to half- 68duplex. 69 70FlowControl 71----------- 72Valid Range: 0-3 (0=none, 1=Rx only, 2=Tx only, 3=Rx&Tx) 73Default Value: Reads flow control settings from the EEPROM 74 75This parameter controls the automatic generation(Tx) and response(Rx) 76to Ethernet PAUSE frames. 77 78InterruptThrottleRate 79--------------------- 80(not supported on Intel(R) 82542, 82543 or 82544-based adapters) 81Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative, 82 4=simplified balancing) 83Default Value: 3 84 85The driver can limit the amount of interrupts per second that the adapter 86will generate for incoming packets. It does this by writing a value to the 87adapter that is based on the maximum amount of interrupts that the adapter 88will generate per second. 89 90Setting InterruptThrottleRate to a value greater or equal to 100 91will program the adapter to send out a maximum of that many interrupts 92per second, even if more packets have come in. This reduces interrupt 93load on the system and can lower CPU utilization under heavy load, 94but will increase latency as packets are not processed as quickly. 95 96The default behaviour of the driver previously assumed a static 97InterruptThrottleRate value of 8000, providing a good fallback value for 98all traffic types,but lacking in small packet performance and latency. 99The hardware can handle many more small packets per second however, and 100for this reason an adaptive interrupt moderation algorithm was implemented. 101 102Since 7.3.x, the driver has two adaptive modes (setting 1 or 3) in which 103it dynamically adjusts the InterruptThrottleRate value based on the traffic 104that it receives. After determining the type of incoming traffic in the last 105timeframe, it will adjust the InterruptThrottleRate to an appropriate value 106for that traffic. 107 108The algorithm classifies the incoming traffic every interval into 109classes. Once the class is determined, the InterruptThrottleRate value is 110adjusted to suit that traffic type the best. There are three classes defined: 111"Bulk traffic", for large amounts of packets of normal size; "Low latency", 112for small amounts of traffic and/or a significant percentage of small 113packets; and "Lowest latency", for almost completely small packets or 114minimal traffic. 115 116In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 117for traffic that falls in class "Bulk traffic". If traffic falls in the "Low 118latency" or "Lowest latency" class, the InterruptThrottleRate is increased 119stepwise to 20000. This default mode is suitable for most applications. 120 121For situations where low latency is vital such as cluster or 122grid computing, the algorithm can reduce latency even more when 123InterruptThrottleRate is set to mode 1. In this mode, which operates 124the same as mode 3, the InterruptThrottleRate will be increased stepwise to 12570000 for traffic in class "Lowest latency". 126 127In simplified mode the interrupt rate is based on the ratio of TX and 128RX traffic. If the bytes per second rate is approximately equal, the 129interrupt rate will drop as low as 2000 interrupts per second. If the 130traffic is mostly transmit or mostly receive, the interrupt rate could 131be as high as 8000. 132 133Setting InterruptThrottleRate to 0 turns off any interrupt moderation 134and may improve small packet latency, but is generally not suitable 135for bulk throughput traffic. 136 137NOTE: InterruptThrottleRate takes precedence over the TxAbsIntDelay and 138 RxAbsIntDelay parameters. In other words, minimizing the receive 139 and/or transmit absolute delays does not force the controller to 140 generate more interrupts than what the Interrupt Throttle Rate 141 allows. 142 143CAUTION: If you are using the Intel(R) PRO/1000 CT Network Connection 144 (controller 82547), setting InterruptThrottleRate to a value 145 greater than 75,000, may hang (stop transmitting) adapters 146 under certain network conditions. If this occurs a NETDEV 147 WATCHDOG message is logged in the system event log. In 148 addition, the controller is automatically reset, restoring 149 the network connection. To eliminate the potential for the 150 hang, ensure that InterruptThrottleRate is set no greater 151 than 75,000 and is not set to 0. 152 153NOTE: When e1000 is loaded with default settings and multiple adapters 154 are in use simultaneously, the CPU utilization may increase non- 155 linearly. In order to limit the CPU utilization without impacting 156 the overall throughput, we recommend that you load the driver as 157 follows: 158 159 modprobe e1000 InterruptThrottleRate=3000,3000,3000 160 161 This sets the InterruptThrottleRate to 3000 interrupts/sec for 162 the first, second, and third instances of the driver. The range 163 of 2000 to 3000 interrupts per second works on a majority of 164 systems and is a good starting point, but the optimal value will 165 be platform-specific. If CPU utilization is not a concern, use 166 RX_POLLING (NAPI) and default driver settings. 167 168RxDescriptors 169------------- 170Valid Range: 80-256 for 82542 and 82543-based adapters 171 80-4096 for all other supported adapters 172Default Value: 256 173 174This value specifies the number of receive buffer descriptors allocated 175by the driver. Increasing this value allows the driver to buffer more 176incoming packets, at the expense of increased system memory utilization. 177 178Each descriptor is 16 bytes. A receive buffer is also allocated for each 179descriptor and can be either 2048, 4096, 8192, or 16384 bytes, depending 180on the MTU setting. The maximum MTU size is 16110. 181 182NOTE: MTU designates the frame size. It only needs to be set for Jumbo 183 Frames. Depending on the available system resources, the request 184 for a higher number of receive descriptors may be denied. In this 185 case, use a lower number. 186 187RxIntDelay 188---------- 189Valid Range: 0-65535 (0=off) 190Default Value: 0 191 192This value delays the generation of receive interrupts in units of 1.024 193microseconds. Receive interrupt reduction can improve CPU efficiency if 194properly tuned for specific network traffic. Increasing this value adds 195extra latency to frame reception and can end up decreasing the throughput 196of TCP traffic. If the system is reporting dropped receives, this value 197may be set too high, causing the driver to run out of available receive 198descriptors. 199 200CAUTION: When setting RxIntDelay to a value other than 0, adapters may 201 hang (stop transmitting) under certain network conditions. If 202 this occurs a NETDEV WATCHDOG message is logged in the system 203 event log. In addition, the controller is automatically reset, 204 restoring the network connection. To eliminate the potential 205 for the hang ensure that RxIntDelay is set to 0. 206 207RxAbsIntDelay 208------------- 209(This parameter is supported only on 82540, 82545 and later adapters.) 210Valid Range: 0-65535 (0=off) 211Default Value: 128 212 213This value, in units of 1.024 microseconds, limits the delay in which a 214receive interrupt is generated. Useful only if RxIntDelay is non-zero, 215this value ensures that an interrupt is generated after the initial 216packet is received within the set amount of time. Proper tuning, 217along with RxIntDelay, may improve traffic throughput in specific network 218conditions. 219 220Speed 221----- 222(This parameter is supported only on adapters with copper connections.) 223Valid Settings: 0, 10, 100, 1000 224Default Value: 0 (auto-negotiate at all supported speeds) 225 226Speed forces the line speed to the specified value in megabits per second 227(Mbps). If this parameter is not specified or is set to 0 and the link 228partner is set to auto-negotiate, the board will auto-detect the correct 229speed. Duplex should also be set when Speed is set to either 10 or 100. 230 231TxDescriptors 232------------- 233Valid Range: 80-256 for 82542 and 82543-based adapters 234 80-4096 for all other supported adapters 235Default Value: 256 236 237This value is the number of transmit descriptors allocated by the driver. 238Increasing this value allows the driver to queue more transmits. Each 239descriptor is 16 bytes. 240 241NOTE: Depending on the available system resources, the request for a 242 higher number of transmit descriptors may be denied. In this case, 243 use a lower number. 244 245TxDescriptorStep 246---------------- 247Valid Range: 1 (use every Tx Descriptor) 248 4 (use every 4th Tx Descriptor) 249 250Default Value: 1 (use every Tx Descriptor) 251 252On certain non-Intel architectures, it has been observed that intense TX 253traffic bursts of short packets may result in an improper descriptor 254writeback. If this occurs, the driver will report a "TX Timeout" and reset 255the adapter, after which the transmit flow will restart, though data may 256have stalled for as much as 10 seconds before it resumes. 257 258The improper writeback does not occur on the first descriptor in a system 259memory cache-line, which is typically 32 bytes, or 4 descriptors long. 260 261Setting TxDescriptorStep to a value of 4 will ensure that all TX descriptors 262are aligned to the start of a system memory cache line, and so this problem 263will not occur. 264 265NOTES: Setting TxDescriptorStep to 4 effectively reduces the number of 266 TxDescriptors available for transmits to 1/4 of the normal allocation. 267 This has a possible negative performance impact, which may be 268 compensated for by allocating more descriptors using the TxDescriptors 269 module parameter. 270 271 There are other conditions which may result in "TX Timeout", which will 272 not be resolved by the use of the TxDescriptorStep parameter. As the 273 issue addressed by this parameter has never been observed on Intel 274 Architecture platforms, it should not be used on Intel platforms. 275 276TxIntDelay 277---------- 278Valid Range: 0-65535 (0=off) 279Default Value: 64 280 281This value delays the generation of transmit interrupts in units of 2821.024 microseconds. Transmit interrupt reduction can improve CPU 283efficiency if properly tuned for specific network traffic. If the 284system is reporting dropped transmits, this value may be set too high 285causing the driver to run out of available transmit descriptors. 286 287TxAbsIntDelay 288------------- 289(This parameter is supported only on 82540, 82545 and later adapters.) 290Valid Range: 0-65535 (0=off) 291Default Value: 64 292 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(This parameter is NOT supported on the 82542-based adapter.) 303Valid Range: 0-1 304Default Value: 1 305 306A value of '1' indicates that the driver should enable IP checksum 307offload for received packets (both UDP and TCP) to the adapter hardware. 308 309Copybreak 310--------- 311Valid Range: 0-xxxxxxx (0=off) 312Default Value: 256 313Usage: insmod e1000.ko copybreak=128 314 315Driver copies all packets below or equaling this size to a fresh RX 316buffer before handing it up the stack. 317 318This parameter is different than other parameters, in that it is a 319single (not 1,1,1 etc.) parameter applied to all driver instances and 320it is also available during runtime at 321/sys/module/e1000/parameters/copybreak 322 323SmartPowerDownEnable 324-------------------- 325Valid Range: 0-1 326Default Value: 0 (disabled) 327 328Allows PHY to turn off in lower power states. The user can turn off 329this parameter in supported chipsets. 330 331KumeranLockLoss 332--------------- 333Valid Range: 0-1 334Default Value: 1 (enabled) 335 336This workaround skips resetting the PHY at shutdown for the initial 337silicon releases of ICH8 systems. 338 339Speed and Duplex Configuration 340============================== 341 342Three keywords are used to control the speed and duplex configuration. 343These keywords are Speed, Duplex, and AutoNeg. 344 345If the board uses a fiber interface, these keywords are ignored, and the 346fiber interface board only links at 1000 Mbps full-duplex. 347 348For copper-based boards, the keywords interact as follows: 349 350 The default operation is auto-negotiate. The board advertises all 351 supported speed and duplex combinations, and it links at the highest 352 common speed and duplex mode IF the link partner is set to auto-negotiate. 353 354 If Speed = 1000, limited auto-negotiation is enabled and only 1000 Mbps 355 is advertised (The 1000BaseT spec requires auto-negotiation.) 356 357 If Speed = 10 or 100, then both Speed and Duplex should be set. Auto- 358 negotiation is disabled, and the AutoNeg parameter is ignored. Partner 359 SHOULD also be forced. 360 361The AutoNeg parameter is used when more control is required over the 362auto-negotiation process. It should be used when you wish to control which 363speed and duplex combinations are advertised during the auto-negotiation 364process. 365 366The parameter may be specified as either a decimal or hexadecimal value as 367determined by the bitmap below. 368 369Bit position 7 6 5 4 3 2 1 0 370Decimal Value 128 64 32 16 8 4 2 1 371Hex value 80 40 20 10 8 4 2 1 372Speed (Mbps) N/A N/A 1000 N/A 100 100 10 10 373Duplex Full Full Half Full Half 374 375Some examples of using AutoNeg: 376 377 modprobe e1000 AutoNeg=0x01 (Restricts autonegotiation to 10 Half) 378 modprobe e1000 AutoNeg=1 (Same as above) 379 modprobe e1000 AutoNeg=0x02 (Restricts autonegotiation to 10 Full) 380 modprobe e1000 AutoNeg=0x03 (Restricts autonegotiation to 10 Half or 10 Full) 381 modprobe e1000 AutoNeg=0x04 (Restricts autonegotiation to 100 Half) 382 modprobe e1000 AutoNeg=0x05 (Restricts autonegotiation to 10 Half or 100 383 Half) 384 modprobe e1000 AutoNeg=0x020 (Restricts autonegotiation to 1000 Full) 385 modprobe e1000 AutoNeg=32 (Same as above) 386 387Note that when this parameter is used, Speed and Duplex must not be specified. 388 389If the link partner is forced to a specific speed and duplex, then this 390parameter should not be used. Instead, use the Speed and Duplex parameters 391previously mentioned to force the adapter to the same speed and duplex. 392 393Additional Configurations 394========================= 395 396 Jumbo Frames 397 ------------ 398 Jumbo Frames support is enabled by changing the MTU to a value larger than 399 the default of 1500. Use the ifconfig command to increase the MTU size. 400 For example: 401 402 ifconfig eth<x> mtu 9000 up 403 404 This setting is not saved across reboots. It can be made permanent if 405 you add: 406 407 MTU=9000 408 409 to the file /etc/sysconfig/network-scripts/ifcfg-eth<x>. This example 410 applies to the Red Hat distributions; other distributions may store this 411 setting in a different location. 412 413 Notes: 414 Degradation in throughput performance may be observed in some Jumbo frames 415 environments. If this is observed, increasing the application's socket buffer 416 size and/or increasing the /proc/sys/net/ipv4/tcp_*mem entry values may help. 417 See the specific application manual and /usr/src/linux*/Documentation/ 418 networking/ip-sysctl.txt for more details. 419 420 - The maximum MTU setting for Jumbo Frames is 16110. This value coincides 421 with the maximum Jumbo Frames size of 16128. 422 423 - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in 424 poor performance or loss of link. 425 426 - Adapters based on the Intel(R) 82542 and 82573V/E controller do not 427 support Jumbo Frames. These correspond to the following product names: 428 Intel(R) PRO/1000 Gigabit Server Adapter 429 Intel(R) PRO/1000 PM Network Connection 430 431 ethtool 432 ------- 433 The driver utilizes the ethtool interface for driver configuration and 434 diagnostics, as well as displaying statistical information. The ethtool 435 version 1.6 or later is required for this functionality. 436 437 The latest release of ethtool can be found from 438 http://ftp.kernel.org/pub/software/network/ethtool/ 439 440 Enabling Wake on LAN* (WoL) 441 --------------------------- 442 WoL is configured through the ethtool* utility. 443 444 WoL will be enabled on the system during the next shut down or reboot. 445 For this driver version, in order to enable WoL, the e1000 driver must be 446 loaded when shutting down or rebooting the system. 447 448Support 449======= 450 451For general information, go to the Intel support website at: 452 453 http://support.intel.com 454 455or the Intel Wired Networking project hosted by Sourceforge at: 456 457 http://sourceforge.net/projects/e1000 458 459If an issue is identified with the released source code on the supported 460kernel with a supported adapter, email the specific information related 461to the issue to e1000-devel@lists.sf.net 462