1Linux* 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- Additional Configurations 13- Support 14 15Identifying Your Adapter 16======================== 17 18The e1000e driver supports all PCI Express Intel(R) Gigabit Network 19Connections, except those that are 82575, 82576 and 82580-based*. 20 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. 24 25For more information on how to identify your adapter, go to the Adapter & 26Driver ID Guide at: 27 28 http://support.intel.com/support/go/network/adapter/idguide.htm 29 30For the latest Intel network drivers for Linux, refer to the following 31website. In the search field, enter your adapter name or type, or use the 32networking link on the left to search for your adapter: 33 34 http://support.intel.com/support/go/network/adapter/home.htm 35 36Command Line Parameters 37======================= 38 39The default value for each parameter is generally the recommended setting, 40unless otherwise noted. 41 42NOTES: 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 46 47InterruptThrottleRate 48--------------------- 49Valid Range: 0,1,3,4,100-100000 (0=off, 1=dynamic, 3=dynamic conservative, 50 4=simplified balancing) 51Default Value: 3 52 53The driver can limit the amount of interrupts per second that the adapter 54will generate for incoming packets. It does this by writing a value to the 55adapter that is based on the maximum amount of interrupts that the adapter 56will generate per second. 57 58Setting InterruptThrottleRate to a value greater or equal to 100 59will program the adapter to send out a maximum of that many interrupts 60per second, even if more packets have come in. This reduces interrupt 61load on the system and can lower CPU utilization under heavy load, 62but will increase latency as packets are not processed as quickly. 63 64The default behaviour of the driver previously assumed a static 65InterruptThrottleRate value of 8000, providing a good fallback value for 66all traffic types, but lacking in small packet performance and latency. 67The hardware can handle many more small packets per second however, and 68for this reason an adaptive interrupt moderation algorithm was implemented. 69 70The driver has two adaptive modes (setting 1 or 3) in which 71it dynamically adjusts the InterruptThrottleRate value based on the traffic 72that it receives. After determining the type of incoming traffic in the last 73timeframe, it will adjust the InterruptThrottleRate to an appropriate value 74for that traffic. 75 76The algorithm classifies the incoming traffic every interval into 77classes. Once the class is determined, the InterruptThrottleRate value is 78adjusted 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", 80for small amounts of traffic and/or a significant percentage of small 81packets; and "Lowest latency", for almost completely small packets or 82minimal traffic. 83 84In dynamic conservative mode, the InterruptThrottleRate value is set to 4000 85for traffic that falls in class "Bulk traffic". If traffic falls in the "Low 86latency" or "Lowest latency" class, the InterruptThrottleRate is increased 87stepwise to 20000. This default mode is suitable for most applications. 88 89For situations where low latency is vital such as cluster or 90grid computing, the algorithm can reduce latency even more when 91InterruptThrottleRate is set to mode 1. In this mode, which operates 92the same as mode 3, the InterruptThrottleRate will be increased stepwise to 9370000 for traffic in class "Lowest latency". 94 95In simplified mode the interrupt rate is based on the ratio of TX and 96RX traffic. If the bytes per second rate is approximately equal, the 97interrupt rate will drop as low as 2000 interrupts per second. If the 98traffic is mostly transmit or mostly receive, the interrupt rate could 99be as high as 8000. 100 101Setting InterruptThrottleRate to 0 turns off any interrupt moderation 102and may improve small packet latency, but is generally not suitable 103for bulk throughput traffic. 104 105NOTE: 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. 110 111NOTE: 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: 116 117 modprobe e1000e InterruptThrottleRate=3000,3000,3000 118 119 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. 125 126RxIntDelay 127---------- 128Valid Range: 0-65535 (0=off) 129Default Value: 0 130 131This value delays the generation of receive interrupts in units of 1.024 132microseconds. Receive interrupt reduction can improve CPU efficiency if 133properly tuned for specific network traffic. Increasing this value adds 134extra latency to frame reception and can end up decreasing the throughput 135of TCP traffic. If the system is reporting dropped receives, this value 136may be set too high, causing the driver to run out of available receive 137descriptors. 138 139CAUTION: 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. 145 146RxAbsIntDelay 147------------- 148Valid Range: 0-65535 (0=off) 149Default Value: 8 150 151This value, in units of 1.024 microseconds, limits the delay in which a 152receive interrupt is generated. Useful only if RxIntDelay is non-zero, 153this value ensures that an interrupt is generated after the initial 154packet is received within the set amount of time. Proper tuning, 155along with RxIntDelay, may improve traffic throughput in specific network 156conditions. 157 158TxIntDelay 159---------- 160Valid Range: 0-65535 (0=off) 161Default Value: 8 162 163This value delays the generation of transmit interrupts in units of 1641.024 microseconds. Transmit interrupt reduction can improve CPU 165efficiency if properly tuned for specific network traffic. If the 166system is reporting dropped transmits, this value may be set too high 167causing the driver to run out of available transmit descriptors. 168 169TxAbsIntDelay 170------------- 171Valid Range: 0-65535 (0=off) 172Default Value: 32 173 174This value, in units of 1.024 microseconds, limits the delay in which a 175transmit interrupt is generated. Useful only if TxIntDelay is non-zero, 176this value ensures that an interrupt is generated after the initial 177packet is sent on the wire within the set amount of time. Proper tuning, 178along with TxIntDelay, may improve traffic throughput in specific 179network conditions. 180 181Copybreak 182--------- 183Valid Range: 0-xxxxxxx (0=off) 184Default Value: 256 185 186Driver copies all packets below or equaling this size to a fresh RX 187buffer before handing it up the stack. 188 189This parameter is different than other parameters, in that it is a 190single (not 1,1,1 etc.) parameter applied to all driver instances and 191it is also available during runtime at 192/sys/module/e1000e/parameters/copybreak 193 194SmartPowerDownEnable 195-------------------- 196Valid Range: 0-1 197Default Value: 0 (disabled) 198 199Allows PHY to turn off in lower power states. The user can set this parameter 200in supported chipsets. 201 202KumeranLockLoss 203--------------- 204Valid Range: 0-1 205Default Value: 1 (enabled) 206 207This workaround skips resetting the PHY at shutdown for the initial 208silicon releases of ICH8 systems. 209 210IntMode 211------- 212Valid Range: 0-2 (0=legacy, 1=MSI, 2=MSI-X) 213Default Value: 2 214 215Allows changing the interrupt mode at module load time, without requiring a 216recompile. If the driver load fails to enable a specific interrupt mode, the 217driver will try other interrupt modes, from least to most compatible. The 218interrupt order is MSI-X, MSI, Legacy. If specifying MSI (IntMode=1) 219interrupts, only MSI and Legacy will be attempted. 220 221CrcStripping 222------------ 223Valid Range: 0-1 224Default Value: 1 (enabled) 225 226Strip the CRC from received packets before sending up the network stack. If 227you have a machine with a BMC enabled but cannot receive IPMI traffic after 228loading or enabling the driver, try disabling this feature. 229 230WriteProtectNVM 231--------------- 232Valid Range: 0,1 233Default Value: 1 234 235If set to 1, configure the hardware to ignore all write/erase cycles to the 236GbE region in the ICHx NVM (in order to prevent accidental corruption of the 237NVM). This feature can be disabled by setting the parameter to 0 during initial 238driver load. 239NOTE: The machine must be power cycled (full off/on) when enabling NVM writes 240via setting the parameter to zero. Once the NVM has been locked (via the 241parameter at 1 when the driver loads) it cannot be unlocked except via power 242cycle. 243 244Additional Configurations 245========================= 246 247 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: 252 253 ifconfig eth<x> mtu 9000 up 254 255 This setting is not saved across reboots. 256 257 Notes: 258 259 - The maximum MTU setting for Jumbo Frames is 9216. This value coincides 260 with the maximum Jumbo Frames size of 9234 bytes. 261 262 - Using Jumbo frames at 10 or 100 Mbps is not supported and may result in 263 poor performance or loss of link. 264 265 - Some adapters limit Jumbo Frames sized packets to a maximum of 266 4096 bytes and some adapters do not support Jumbo Frames. 267 268 - Jumbo Frames cannot be configured on an 82579-based Network device, if 269 MACSec is enabled on the system. 270 271 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: 276 277 https://kernel.org/pub/software/network/ethtool/ 278 279 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. 281 282 Speed and Duplex 283 ---------------- 284 Speed and Duplex are configured through the ethtool* utility. For 285 instructions, refer to the ethtool man page. 286 287 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. 291 292 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. 295 296 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>. 298 299Support 300======= 301 302For general information, go to the Intel support website at: 303 304 www.intel.com/support/ 305 306or the Intel Wired Networking project hosted by Sourceforge at: 307 308 http://sourceforge.net/projects/e1000 309 310If an issue is identified with the released source code on the supported 311kernel with a supported adapter, email the specific information related 312to the issue to e1000-devel@lists.sf.net 313
