This is some further information from ATTO on the best settings to use for the Ethernet LTO.
General
# Enable TCP Checksum offloading for Rx and Tx
net.link.generic.system.hwcksum_tx=1
net.link.generic.system.hwcksum_rx=1
# Change Rx and Tx Buffer Auto Max to 4 MB
net.inet.tcp.autorcvbufmax=4194304
net.inet.tcp.autosndbufmax=4194304
# Responds after every packet (ON)
net.inet.tcp.delayed_ack=0
# Enable HW LRO if it’s not on (gates HW LRO)
net.inet.tcp.lro=1
# Enable TSO if it's not on (gates TSO)
net.inet.tcp.tso=1
[symply_8100T.nsmb]
signing_required=no
[symply_8100T.networksetup]
# Set MTU to 9000
setMTU=9000
If using ATTO FastFrame4 (Broadcom Chip Set)
# Enable HW LRO
HwLro=true
# Turn on SW LRO if it’s not on
SwLro=true
# Turn on TSO if it's not on
Tso=true
If using ATTO FastFrame3 (Mellanox Chip Set)
# Enable HW LRO
net.$DRV.$DEV.hw_lro=16384
# Turn on SW LRO if it’s not on
net.$DRV.$DEV.sw_lro=65536
# Turn on TSO if it's not on
net.$DRV.$DEV.tso4=65536