igb.7

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.
.TH igb 1 "March 2, 2021"
.SH NAME
igb \-This file describes the Linux* Base Driver
for the Gigabit Family of Adapters.
.SH SYNOPSIS
.PD 0.4v
modprobe igb [<option>=<VAL1>,<VAL2>,...]
.PD 1v
.SH DESCRIPTION
This driver is intended for \fB2.6.30\fR and later kernels. A version of the driver may already be included by your distribution and/or the kernel.org kernel.

.LP
This driver is only supported as a loadable module at this time. Intel is not supplying patches against the kernel source to allow for static linking of the drivers.


For questions related to hardware requirements, refer to the documentation
supplied with your Intel adapter. All hardware requirements listed apply to
use with Linux.
.SH OPTIONS
The following optional parameters are used by entering them on the
command line with the modprobe command.
For example:
.IP
modprobe igb InterruptThrottleRate=16000,16000
.LP
.B DMAC
.IP
.B Valid Range: 0, 1, 250, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000
.IP
This parameter enables or disables DMA Coalescing feature. Values are in microseconds and set the internal DMA Coalescing internal timer.
.IP
DMA (Direct Memory Access) allows the network device to move packet data directly to the system's memory, reducing CPU utilization. However, the frequency and random intervals at which packets arrive do not allow the system to enter a lower power state. DMA Coalescing allows the adapter to collect packets before it initiates a DMA event. This may increase network latency but also increases the chances that the system will enter a lower power state.
.IP
Turning on DMA Coalescing may save energy with kernel 2.6.32 and newer. DMA Coalescing must be enabled across all active ports in order to save platform power.
.LP
.B EEE (Energy Efficient Ethernet)
.IP
.B Valid Range: 0-1
.IP
0 = Disables EEE
.IP
1 = Enables EEE
.IP

A link between two EEE-compliant devices will result in periodic bursts of data followed by periods where the link is in an idle state. This Low Power Idle (LPI) state is supported at 1 Gbps and 100 Mbps link speeds.

NOTES:
- EEE support requires auto-negotiation.
- Both link partners must support EEE.
- EEE is not supported on all Intel(R) Ethernet Network devices or at all link speeds.

Example:

# ethtool --show-eee <ethX>
# ethtool --set-eee <ethX> [eee on|off]
.LP
.B IntMode
.IP
.B Valid Range: 0-2 (0 = Legacy Int, 1 = MSI and 2 = MSI-X)
.IP
IntMode controls the allowed load time control over the type of interrupt
registered for by the driver. MSI-X is required for multiple queue
support, and some kernels and combinations of kernel .config options
will force a lower level of interrupt support.
'cat /proc/interrupts' will show different values for each type of interrupt.
.LP
.B InterruptThrottleRate
.IP
.B Valid Range:
0=off
1=dynamic
3=dynamic conservative
<min_ITR>-<max_ITR>
.IP
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.
.IP
0 = Setting InterruptThrottleRate to 0 turns off any interrupt moderation
  and may improve small packet latency. However, this is generally not
  suitable for bulk throughput traffic due to the increased CPU utilization
  of the higher interrupt rate.
.IP
1 = Setting InterruptThrottleRate to Dynamic mode attempts to moderate
  interrupts per vector while maintaining very low latency. This can
  sometimes cause extra CPU utilization. If planning on deploying igb
  in a latency sensitive environment, this parameter should be considered.
.IP
<min_ITR>-<max_ITR> = 100-100000
  Setting InterruptThrottleRate to a value greater or equal to <min_ITR>
  will program the adapter to send at most 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.

.IP
NOTE: InterruptThrottleRate is NOT supported by 82542, 82543, or 82544-based adapters.
.LP
.B Jumbo Frames
.IP
Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU) to a value larger than the default value of 1500.

.IP
Use the ip command to increase the MTU size. For example, enter the following where <ethX> is the interface number:

.IP
# ip link set mtu 9000 dev <ethX>
.IP
# ip link set up dev <ethX>

.LP
NOTE: The maximum MTU setting for jumbo frames is 9216. This corresponds to the maximum jumbo frame size of 9234 bytes.

NOTE: Using jumbo frames at 10 or 100 Mbps is not supported and may result in poor performance or loss of link.

NOTE: Packet loss may have a greater impact on throughput when you use jumbo frames. If you observe a drop in performance after enabling jumbo frames, enabling flow control may mitigate the issue.
See the section "Jumbo Frames" in the Readme.
.LP
.B LLIPort
.IP
.B Valid Range: 0-65535
.IP
LLI is configured with the LLIPort command-line parameter, which specifies
which TCP port should generate Low Latency Interrupts.
.IP
For example, using LLIPort=80 would cause the board to generate an immediate
interrupt upon receipt of any packet sent to TCP port 80 on the local machine.
.IP
WARNING: Enabling LLI can result in an excessive number of interrupts/second
that may cause problems with the system and in some cases may cause a kernel
panic.
.LP
.B LLIPush
.IP
.B Valid Range: 0-1
.IP
LLIPush can be set to be enabled or disabled (default). It is most effective
in an environment with many small transactions.
.IP
NOTE: Enabling LLIPush may allow a denial of service attack.
.LP
.B LLISize
.IP
.B Valid Range: 0-1500
.IP
LLISize causes an immediate interrupt if the board receives a packet smaller
than the specified size.
.LP
.B LRO
.IP
.B Valid Range: 0(off), 1(on)
Large Receive Offload (LRO) is a technique for increasing inbound throughput
of high-bandwidth network connections by reducing CPU overhead. It works by
aggregating multiple incoming packets from a single stream into a larger
buffer before they are passed higher up the networking stack, thus reducing
the number of packets that have to be processed. LRO combines multiple
Ethernet frames into a single receive in the stack, thereby potentially
decreasing CPU utilization for receives.
.IP
NOTE: LRO requires 2.4.22 or later kernel version.
.IP
IGB_NO_LRO is a compile time flag. The user can enable it at compile time to add support for LRO from the driver. The flag is used by adding CFLAGS_EXTRA="-DIGB_NO_LRO" to the make file when it's being compiled.
# make CFLAGS_EXTRA="-DIGB_NO_LRO" install
.IP
You can verify that the driver is using LRO by looking at these counters in ethtool:
.LP
- lro_aggregated - counts total packets that were combined
.LP
- lro_flushed - counts the number of packets flushed out of LRO
.LP
- lro_recycled - counts the number of buffers returned to the ring from
  recycling
.IP
NOTE: IPv6 and UDP are not supported by LRO.
.LP
.B max_vfs
This parameter adds support for SR-IOV. It causes the driver to spawn up to max_vfs worth of virtual functions.
.IP
.B Valid Range:  0-7
.IP
If the value is greater than 0 it will also force the VMDq parameter to be 1 or more.
.IP
.IP
.LP
.B MDD (Malicious Driver Detection)
.IP
.B Valid Range: 0-1
.IP
0 = Disabled
.IP
1 = Enabled
.IP
This parameter is only relevant for I350 devices operating in SR-IOV mode.
When this parameter is set, the driver detects malicious VF driver and
disables its Tx/Rx queues until a VF driver reset occurs.
.LP
.B Node
.IP
.B Valid Range: 0-n
.IP
0 - n: where n is the number of the NUMA node that should be used to allocate
memory for this adapter port.
.IP
-1: uses the driver default of allocating memory on whichever processor is
running modprobe.
.IP
The Node parameter allows you to choose which NUMA node you want to have the
adapter allocate memory from. All driver structures, in-memory queues, and
receive buffers will be allocated on the node specified. This parameter is
only useful when interrupt affinity is specified; otherwise, part of the
interrupt time could run on a different core than where the memory is
allocated causing slower memory access and impacting throughput, CPU, or both.
.LP
.B QueuePairs
.IP
.B Valid Range: 0-1
.IP
If set to 0, when MSI-X is enabled, the Tx and Rx will attempt to occupy
separate vectors.
.IP
This option can be overridden to 1 if there are not sufficient interrupts
available. This can occur if any combination of RSS, VMDQ, and max_vfs results
in more than 4 queues being used.
.LP
.B RSS
.IP
.B Valid Range: 0-8
.IP
0 = Assign up to the lesser value of the number of CPUs or the number of queues
.IP
X = Assign X queues, where X is less than or equal to the maximum number of
queues (8 queues).
.IP
NOTE: For 82575-based adapters, the maximum number of queues is 4; for
82576-based and newer adapters it is 8; for I210-based adapters it is 4
queues; and for I211-based adapters it is 2 queues.
.IP
This parameter is also affected by the VMDq parameter in that it will limit
the queues more. For example, if you set an 82575 device to VMDQ Mode 2, you will only be able to set 3 RSS queues. See the following table.
.IP
Model	VMDQ Mode
.IP
Number	0 1 2 3+
.IP
82575	4 4 3 1
.IP
82576	8 2 2 2
.IP
82580	8 1 1 1
.LP
.B VMDQ
.IP
.B Valid Range: 0-4 on 82575-based adapters; 0-8 for 82576/82580-based adapters
.IP
Supports enabling VMDq pools as this is needed to support SR-IOV.
.IP
0 = Disabled
.IP
1 = Sets the netdev as pool 0
.IP
2+ = Add additional queues but they currently are not used
.IP
This parameter is forced to 1 or more if the max_vfs module parameter is used.
In addition, the number of queues available for RSS is limited if this is set
to 1 or greater.
.LP
.B DV (Double VLAN)
.IP
.B Valid Range: 0-1
.IP
0 = Disabled
.IP
1 = Enabled
.IP
Control Double VLAN mode on device. If enabled hardware assumes that at least
single vlan header present in packet buffer and second header is skipped to
enable rest of L2/L3 offloading processing (e.g. RSS). It is disabled by default
since VID filtering, if enabled, is done in software by driver and not compatible
with VMDq.
.LP
.B ethtool
.LP
The driver utilizes the ethtool interface for driver configuration and diagnostics, as well as displaying statistical information. The latest ethtool version is required for this functionality. Download it at:
https://kernel.org/pub/software/network/ethtool/


.SH SUPPORT
.LP
For additional information regarding building and installation, see the
README
included with the driver.
For general information, go to the Intel support website at:
.B http://www.intel.com/support/

.LP
If an issue is identified with the released source code on a supported kernel with a supported adapter, email the specific information related to the issue to e1000-devel@lists.sf.net.
.LP