Something trigger network to become terribly slow until reboot

[X512]

This is hrev53639 x86 gcc2hybrid.

After something happens (I don't know what exactly) network become terribly slow, including LAN. Speed is recovered after reboot.

atheros813x driver is used.

Network controllers installed:

device Network controller [2|80|0]
  vendor 8086: Intel Corporation
  device 08b1: Wireless 7260

device Network controller (Ethernet controller) [2|0|0]
  vendor 1969: Qualcomm Atheros
  device 1091: AR8161 Gigabit Ethernet

device Network controller (Ethernet controller) [2|0|0]
  vendor 8086: Intel Corporation
  device 153b: Ethernet Connection I217-V

[waddlesplash]

Duplicate of #12876 maybe?

IIRC, this was briefly investigated by a developer (cannot remember who) and determined that the problem is likely in the TCP stack related to scaling of some sort.

[X512]

Network speed degrades instantly, not gradually. Long time since boot seems not required to trigger issue.

[waddlesplash]

Please retest under a recent nightly, the DMA changes may affect this.

[waddlesplash]

At least for me the problem seems to replicate with iperf on localhost as observed in #18203.