If you are using an Intel 10G Ethernet card with a 82598GB chipset, you’re using ixgbe(4). You may want to set the net.inet.tcp.sosend_agglim sysctl to a value over 12 in certain circumstances, as described by Francois Tigeot.
is this specific to the intel or to any 10gig nic? broadcoms and what not?
The commit itself mentions only the ixgbe card, so my first guess is yes, Intel only.
Note that the improvement happens only in single-stream situations, so it may not matter if you’re dealing with a situation where you have multiple connections adding up to fill the bandwidth on a 10G card.
Francois is on #dragonflybsd EFNet IRC frequently; that may be an easy way to follow up.
This ixgbe driver should work with all recent Intel 10G ethernet nics, both 82598 and 82599 based.
The X520 and X540 are among the list; I’ve tested the driver with a pair of X520 10G-baseT adapters.
The net.inet.tcp.sosend_agglim sysctl should not be used blindly; setting it to 12 will increase latency on 1Gb/s connections.
Sepherosa Ziehau is planning to make this sysctl device specific in the future.
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