Under load my networking drops. I can recover with a "service network restart" (this type of soft restart has only worked with the current SF driver, version 2.1.4).
I dumped a bunch of info on pastebin:
From the syslog it looks like the adapter resets in this condition, and this kills my bridging which basically kills my entire network since all my eth5 VLAN interfaces are hooked into the bridges.
Why is this IRQ unhandled by the card? If you look at the pastebin (/proc/interrupts) it's clear that irq 194 is attached to eth5 (running the e1000e driver).
Google'ing around finds threads indicating potential problems with some PCIe bridge chips. I attached an lspci dump in case that might help identify known, buggy hardware.