TSO、UFO、GSO、LRO、GRO和RSS介绍（ethtool命令）

更加详细的说明，请参看连接：
linux tcp GSO和TSO实现
linux tcp GSO和TSO实现详解

1. ethtool工具命令介绍

# ethtool -h
RTL Ethtool(2.6.36):
Usage:
ethtool DEVNAME Display standard information about device
        ethtool -s|--change DEVNAME     Change generic options
                [ speed %d ]
                [ duplex half|full ]
                [ port tp|aui|bnc|mii|fibre ]
                [ autoneg on|off ]
                [ advertise %x ]
                [ phyad %d ]
                [ xcvr internal|external ]
                [ wol p|u|m|b|a|g|s|d... ]
                [ sopass %x:%x:%x:%x:%x:%x ]
                [ msglvl %d | msglvl type on|off ... ]
        ethtool -a|--show-pause DEVNAME Show pause options
        ethtool -A|--pause DEVNAME      Set pause options
                [ autoneg on|off ]
                [ rx on|off ]
                [ tx on|off ]
        ethtool -c|--show-coalesce DEVNAME      Show coalesce options
        ethtool -C|--coalesce DEVNAME   Set coalesce options
                [adaptive-rx on|off]
                [adaptive-tx on|off]
                [rx-usecs N]
                [rx-frames N]
                [rx-usecs-irq N]
                [rx-frames-irq N]
                [tx-usecs N]
                [tx-frames N]
                [tx-usecs-irq N]
                [tx-frames-irq N]
                [stats-block-usecs N]
                [pkt-rate-low N]
                [rx-usecs-low N]
                [rx-frames-low N]
                [tx-usecs-low N]
                [tx-frames-low N]
                [pkt-rate-high N]
                [rx-usecs-high N]
                [rx-frames-high N]
                [tx-usecs-high N]
                [tx-frames-high N]
                [sample-interval N]
        ethtool -g|--show-ring DEVNAME  Query RX/TX ring parameters
        ethtool -G|--set-ring DEVNAME   Set RX/TX ring parameters
                [ rx N ]
                [ rx-mini N ]
                [ rx-jumbo N ]
                [ tx N ]
        ethtool -k|--show-offload DEVNAME       Get protocol offload information
        ethtool -K|--offload DEVNAME    Set protocol offload
                [ rx on|off ]
                [ tx on|off ]
                [ sg on|off ]
                [ tso on|off ]
                [ ufo on|off ]
                [ gso on|off ]
                [ gro on|off ]
                [ lro on|off ]
                [ rxvlan on|off ]
                [ txvlan on|off ]
                [ ntuple on|off ]
                [ rxhash on|off ]
        ethtool -i|--driver DEVNAME     Show driver information
        ethtool -d|--register-dump DEVNAME      Do a register dump
                [ raw on|off ]
                [ file FILENAME ]
        ethtool -e|--eeprom-dump DEVNAME        Do a EEPROM dump
                [ raw on|off ]
                [ offset N ]
                [ length N ]
        ethtool -E|--change-eeprom DEVNAME      Change bytes in device EEPROM
                [ magic N ]
                [ offset N ]
                [ length N ]
                [ value N ]
        ethtool -r|--negotiate DEVNAME  Restart N-WAY negotation
        ethtool -p|--identify DEVNAME   Show visible port identification (e.g. blinking)
               [ TIME-IN-SECONDS ]
        ethtool -t|--test DEVNAME       Execute adapter self test
               [ online | offline ]
        ethtool -S|--statistics DEVNAME Show adapter statistics
        ethtool -n|--show-nfc DEVNAME   Show Rx network flow classificationoptions
                [ rx-flow-hash tcp4|udp4|ah4|sctp4|tcp6|udp6|ah6|sctp6 ]
        ethtool -f|--flash DEVNAME      FILENAME Flash firmware image from the specified file to a region on the device
               [ REGION-NUMBER-TO-FLASH ]
        ethtool -N|--config-nfc DEVNAME Configure Rx network flow classification options
                [ rx-flow-hash tcp4|udp4|ah4|sctp4|tcp6|udp6|ah6|sctp6 m|v|t|s|d|f|n|r... ]
        ethtool -x|--show-rxfh-indir DEVNAME    Show Rx flow hash indirection
        ethtool -X|--set-rxfh-indir DEVNAME     Set Rx flow hash indirection
                equal N | weight W0 W1 ...
        ethtool -U|--config-ntuple DEVNAME      Configure Rx ntuple filters and actions
                { flow-type tcp4|udp4|sctp4
                  [ src-ip ADDR [src-ip-mask MASK] ]
                  [ dst-ip ADDR [dst-ip-mask MASK] ]
                  [ src-port PORT [src-port-mask MASK] ]
                  [ dst-port PORT [dst-port-mask MASK] ]
                | flow-type ether
                  [ src MAC-ADDR [src-mask MASK] ]
                  [ dst MAC-ADDR [dst-mask MASK] ]
                  [ proto N [proto-mask MASK] ] }
                [ vlan VLAN-TAG [vlan-mask MASK] ]
                [ user-def DATA [user-def-mask MASK] ]
                action N
        ethtool -u|--show-ntuple DEVNAME        Get Rx ntuple filters and actions

        ethtool -P|--show-permaddr DEVNAME      Show permanent hardware address
        ethtool -h|--help               Show this help
#
#

2. 查看网卡的部分属性

# ethtool -k eth0
Offload parameters for eth0:
rx-checksumming: on
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: on
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: off
rx-vlan-offload: off
tx-vlan-offload: off
ntuple-filters: off
receive-hashing: off
#

这些offload特性都是为了提升网络收/发性能。TSO、UFO和GSO是对应网络发送，在接收方向上对应的是LRO、GRO。

• TSO

TSO(TCP Segmentation Offload)，是一种利用网卡对TCP数据包分片，减轻CPU负荷的一种技术，有时也被叫做 LSO (Large segment offload) ，TSO是针对TCP的，UFO是针对UDP的。如果硬件支持 TSO功能，同时也需要硬件支持的TCP校验计算和分散/聚集 (Scatter Gather) 功能。

• GSO

GSO(Generic Segmentation Offload)，它比TSO更通用，基本思想就是尽可能的推迟数据分片直至发送到网卡驱动之前，此时会检查网卡是否支持分片功能（如TSO、UFO）,如果支持直接发送到网卡，如果不支持就进行分片后再发往网卡。这样大数据包只需走一次协议栈，而不是被分割成几个数据包分别走，这就提高了效率。

• LRO

LRO(Large Receive Offload)，通过将接收到的多个TCP数据聚合成一个大的数据包，然后传递给网络协议栈处理，以减少上层协议栈处理 开销，提高系统接收TCP数据包的能力。

• GRO

GRO(Generic Receive Offload)，基本思想跟LRO类似，克服了LRO的一些缺点，更通用。后续的驱动都使用GRO的接口，而不是LRO。

• RSS

RSS(Receive Side Scaling)，是一项网卡的新特性，俗称多队列。具备多个RSS队列的网卡，可以将不同的网络流分成不同的队列，再分别将这些队列分配到多个CPU核心上进行处理，从而将负荷分散，充分利用多核处理器的能力。

3. 关闭、打开这些属性

ethtool -K eth1 gro off
ethtool -K eth1 tso off

# 注意：使用大写的K