Performance drop on SFC interface (around 30%)

Hello netdev,
we see a performance drop (about ~30%) on sfc driver (SFC9020) when
performing netperf TCP maerts test. It seems it started from 4.7-rc0.

Which commit/change could cause this regression? Any hints?

I opened a bugzilla [0] where you can find images with results.

[0] https://bugzilla.kernel.org/show_bug.cgi?id=120461

-- 
Ota