On 06.12.19 10:12, Johannes Berg wrote:
On Fri, 2019-12-06 at 09:41 +0100, Johannes Berg wrote:
Maybe somehow TSO is interacting badly with the TXQs and the tracking
here, since TSO makes the traffic *very* bursty? A 64k packet in the
driver will typically expand to 9 or 10 A-MSDUs I think?
No, that all seems well. Without TSO (with the trivial mac80211 patch to
let me turn it off with ethtool) I get about 890Mbps, so about 5% less.
That's not actually *that* bad, I guess due to software A-MSDU in
mac80211, but it's not really the right direction :)
If you try this test again while setting coverage class higher (20000m
or so), you *will* notice the difference a *lot* more (>50%) :-)
Even when the actual devices are only a few meters apart.
Changing wmem_max/tcp_mem to outrageous values also didn't really make
any difference.
I guess it's time to see if I can poke into the TCP stack to figure out
what's going on...
johannes
