Linux Base Driver for Intel(R) Ethernet Multi-host Controller

문서 범위와 adapter 식별

이 문서는 `GPL-2.0+` 라이선스를 따릅니다.

Intel(R) Ethernet Multi-host Controller용 Linux Base Driver

2018년 8월 20일

Copyright(c) 2015-2018 Intel Corporation.

목차

• Adapter 식별
• 추가 configuration
• Performance tuning
• 알려진 문제
• 지원

Adapter 식별

이 release의 드라이버는 Intel(R) Ethernet Multi-host Controller 기반 device와 호환됩니다.

adapter 식별 방법과 최신 Intel network driver는 Intel Support website `https://www.intel.com/support`를 참고하십시오.

.. SPDX-License-Identifier: GPL-2.0+

=============================================================
Linux Base Driver for Intel(R) Ethernet Multi-host Controller
=============================================================

August 20, 2018
Copyright(c) 2015-2018 Intel Corporation.

Contents
========
- Identifying Your Adapter
- Additional Configurations
- Performance Tuning
- Known Issues
- Support

Identifying Your Adapter
========================
The driver in this release is compatible with devices based on the Intel(R)
Ethernet Multi-host Controller.

For information on how to identify your adapter, and for the latest Intel
network drivers, refer to the Intel Support website:
https://www.intel.com/support

Flow Control과 Virtual Function

Flow Control

Intel(R) Ethernet Switch Host Interface Driver는 Flow Control을 지원하지 않으며 pause frame을 보내지 않습니다. 이로 인해 frame이 drop될 수 있습니다.

Virtual Function(VF)

sysfs로 VF를 활성화합니다. 유효 범위는 `0-64`입니다.

echo $num_vf_enabled > /sys/class/net/$dev/device/sriov_numvfs //enable VFs
echo 0 > /sys/class/net/$dev/device/sriov_numvfs //disable VFs

device와 driver 어느 쪽도 VF가 configuration space에 mapping되는 방식을 제어하지 않습니다. bus layout은 operating system마다 다르며 지원하는 OS에서는 sysfs에서 mapping을 확인할 수 있습니다.

SR-IOV mode가 활성화되어도 hardware VLAN filtering과 VLAN tag stripping/insertion은 계속 활성화됩니다. 새 VLAN filter를 추가하기 전에 이전 VLAN filter를 제거해야 합니다.

ip link set eth0 vf 0 vlan 100 // set vlan 100 for VF 0
ip link set eth0 vf 0 vlan 0   // delete vlan 100
ip link set eth0 vf 0 vlan 200 // set a new vlan 200 for VF 0

Flow Control
------------
The Intel(R) Ethernet Switch Host Interface Driver does not support Flow
Control. It will not send pause frames. This may result in dropped frames.


Virtual Functions (VFs)
-----------------------
Use sysfs to enable VFs.
Valid Range: 0-64

For example::

    echo $num_vf_enabled > /sys/class/net/$dev/device/sriov_numvfs //enable VFs
    echo 0 > /sys/class/net/$dev/device/sriov_numvfs //disable VFs

NOTE: Neither the device nor the driver control how VFs are mapped into config
space. Bus layout will vary by operating system. On operating systems that
support it, you can check sysfs to find the mapping.

NOTE: When SR-IOV mode is enabled, hardware VLAN filtering and VLAN tag
stripping/insertion will remain enabled. Please remove the old VLAN filter
before the new VLAN filter is added. For example::

    ip link set eth0 vf 0 vlan 100        // set vlan 100 for VF 0
    ip link set eth0 vf 0 vlan 0        // Delete vlan 100
    ip link set eth0 vf 0 vlan 200        // set a new vlan 200 for VF 0

Jumbo Frame

추가 기능과 configuration

Jumbo Frame

MTU(Maximum Transmission Unit)를 default `1500`보다 크게 변경하면 Jumbo Frame 지원이 활성화됩니다.

ifconfig 또는 ip command로 MTU를 늘릴 수 있습니다.

ifconfig eth<x> mtu 9000 up
ip link set mtu 9000 dev eth<x>
ip link set up dev eth<x>

이 설정은 reboot 후 유지되지 않습니다. 영구 설정은 RHEL의 `/etc/sysconfig/network-scripts/ifcfg-eth<x>` 또는 SLES의 `/etc/sysconfig/network/<config_file>`에 `MTU=9000`을 추가합니다.

Jumbo Frame의 최대 MTU는 `15342`, 최대 frame size는 `15364 bytes`입니다.

드라이버는 jumbo packet 하나를 수신할 때 page 크기 buffer 여러 개를 사용하려고 합니다. 이는 receive packet 할당 시 buffer starvation을 피하는 데 도움이 됩니다.

Additional Features and Configurations
======================================

Jumbo Frames
------------
Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU)
to a value larger than the default value of 1500.

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

    ifconfig eth<x> mtu 9000 up

Alternatively, you can use the ip command as follows::

    ip link set mtu 9000 dev eth<x>
    ip link set up dev eth<x>

This setting is not saved across reboots. The setting change can be made
permanent by adding 'MTU=9000' to the file:

- For RHEL: /etc/sysconfig/network-scripts/ifcfg-eth<x>
- For SLES: /etc/sysconfig/network/<config_file>

NOTE: The maximum MTU setting for Jumbo Frames is 15342. This value coincides
with the maximum Jumbo Frames size of 15364 bytes.

NOTE: This driver will attempt to use multiple page sized buffers to receive
each jumbo packet. This should help to avoid buffer starvation issues when
allocating receive packets.

Generic Receive Offload

Generic Receive Offload(GRO)

드라이버는 kernel 내부의 software GRO 구현을 지원합니다. GRO는 Rx traffic을 더 큰 data chunk로 합쳐 large Rx load에서 CPU utilization을 크게 줄일 수 있습니다.

GRO는 이전 LRO interface의 발전형으로 TCP 이외의 protocol도 합칠 수 있습니다. bridging과 iSCSI처럼 LRO에 문제가 되는 configuration에서도 안전하게 사용할 수 있습니다.

Generic Receive Offload, aka GRO
--------------------------------
The driver supports the in-kernel software implementation of GRO. GRO has
shown that by coalescing Rx traffic into larger chunks of data, CPU
utilization can be significantly reduced when under large Rx load. GRO is an
evolution of the previously-used LRO interface. GRO is able to coalesce
other protocols besides TCP. It's also safe to use with configurations that
are problematic for LRO, namely bridging and iSCSI.

Filtering용 ethtool command

Filtering을 지원하는 ethtool command와 option

`-n --show-nfc`는 receive network flow classification configuration을 조회합니다.

`rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6`는 지정한 network traffic type의 hash option을 조회합니다.

`-N --config-nfc`는 receive network flow classification을 구성합니다.

`rx-flow-hash ... m|v|t|s|d|f|n|r` 형식으로 지정한 traffic type의 hash option을 구성합니다.

• `udp4`: IPv4 위의 UDP
• `udp6`: IPv6 위의 UDP
• `f`: Rx packet Layer 4 header의 byte 0과 1을 hash
• `n`: Rx packet Layer 4 header의 byte 2와 3을 hash

Supported ethtool Commands and Options for Filtering
----------------------------------------------------
-n --show-nfc
  Retrieves the receive network flow classification configurations.

rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6
  Retrieves the hash options for the specified network traffic type.

-N --config-nfc
  Configures the receive network flow classification.

rx-flow-hash tcp4|udp4|ah4|esp4|sctp4|tcp6|udp6|ah6|esp6|sctp6 m|v|t|s|d|f|n|r
  Configures the hash options for the specified network traffic type.

- udp4: UDP over IPv4
- udp6: UDP over IPv6
- f Hash on bytes 0 and 1 of the Layer 4 header of the rx packet.
- n Hash on bytes 2 and 3 of the Layer 4 header of the rx packet.

알려진 문제와 troubleshooting

알려진 문제와 troubleshooting

Linux KVM 아래의 64-bit Microsoft Windows Server 2012/R2 guest OS에서 SR-IOV를 활성화하는 경우를 다룹니다.

KVM Hypervisor/VMM은 PCIe device를 VM에 direct assignment하는 기능을 지원합니다. 여기에는 전통적인 PCIe device와 Intel Ethernet Controller XL710 기반 SR-IOV-capable device가 포함됩니다.

Known Issues/Troubleshooting
============================

Enabling SR-IOV in a 64-bit Microsoft Windows Server 2012/R2 guest OS under Linux KVM
-------------------------------------------------------------------------------------
KVM Hypervisor/VMM supports direct assignment of a PCIe device to a VM. This
includes traditional PCIe devices, as well as SR-IOV-capable devices based on
the Intel Ethernet Controller XL710.

지원

지원

일반 정보는 Intel support website `https://www.intel.com/support/`를 참고하십시오.

지원되는 adapter와 kernel에서 공개 source code의 문제가 확인되면 구체적인 정보를 `intel-wired-lan@lists.osuosl.org`로 보내십시오.

Support
=======
For general information, go to the Intel support website at:
https://www.intel.com/support/

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 intel-wired-lan@lists.osuosl.org.