[PATCH 0/1][SRU][B][E][F][G][OEM-OSP1-B][OEM-5.6] Slow send speed with Intel I219-V on Ubuntu 18.04.1

[AceLan Kao]

BugLink: https://bugs.launchpad.net/bugs/1802691

[Impact]
The throughput measured by iperf3 is around 70% of 1Gbps (Intel I219-LM
[8086:15b7])
I219 is a rather cheap NIC and it impacts its throughput if TSO(TCP
segmentation offload) is enabled.

[Fix]
Disable TSO on NIC and move this task back to CPU fixes this issue.
The impact of CPU loading is little to none.
On target machine with Xeon(R) CPU E3-1505L v6 @ 2.20GHz(4c8t), the CPU
usage of iperf3 increases from 1% to 4%

[Verify]
Origin
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 918 MBytes 770 Mbits/sec 0 sender
[ 4] 0.00-10.00 sec 916 MBytes 769 Mbits/sec receiver

Becomes
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 1.09 GBytes 936 Mbits/sec 0 sender
[ 4] 0.00-10.00 sec 1.09 GBytes 934 Mbits/sec receiver

[Regression Potential]
Low, disable TSO on Ethernet chip will move the TCP segmentation task
to CPU. This increase CPU loading a little bit, and should not introduce
any regression.

Kai-Heng Feng (1):
  e1000e: Disable TSO for buffer overrun workaround

 drivers/net/ethernet/intel/e1000e/netdev.c | 4 ++++
 1 file changed, 4 insertions(+)

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2.25.1