Re: tcp wifi upload performance and lots of ACKs

On Mon, Jun 4, 2012 at 9:29 PM, Ben Greear [off-list ref] wrote:

I'm going some TCP performance testing on wifi -> LAN interface connections.
 With
UDP, we can get around 250Mbps of payload throughput.  With TCP, max is
about 80Mbps.

I think the problem is that there are way too many ACK packets, and
bi-directional
traffic on wifi interfaces really slows things down.  (About 7000 pkts per
second in
upload direction, 2000 pps download.  And the vast majority of the download
pkts
are 66 byte ACK pkts from what I can tell.)

Kernel is 3.3.7+

Anyone know of any tuning parameters that would let the receiving socket
wait a
bit longer and send more ACK data in fewer packets?

An ACK is generated after every second full sized segment or a timeout
expires.

Currently, there is no way to tune these parameters. Here is an experimental
patch [1]. If anyone, thinks that this patch has a chance to get accepted
I will be happily try to further improve it.

Packet traces and other info available if anyone wants to take a look.

thanks,
Daniel.

[1] http://marc.info/?l=linux-netdev&m=131983649130350&w=2