Patrick, glad to see you got your issue sorted out! I've experienced a
similar issue with network cables once or twice.
And now a word from the original poster... :-)
On 2/8/20 5:18 PM, Dave Ulrick wrote:
I've ordered a PCIE Gigabit Ethernet card in hopes that it will have a
chipset that isn't affected by this issue.
My issue was very different than Patrick's...mine is that transmit
performance was 7% worse than receive performance when using a network
interface with the RTL8168evl chipset: 870 Mbps transmit, 940 Mbps receive.
The PCIE card arrived today and is now installed. It has the RTL8168e
chipset:
[ 3.007475] r8169 0000:03:00.0 eth0: RTL8168e/8111e,
34:e8:94:db:6c:bc, XID 2c2, IRQ 31
It has fixed my Ethernet performance issue!
I'm back to 940 Mbits/sec both transmit and receive. iperf3 transmit
results:
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 115 MBytes 963 Mbits/sec 48 413 KBytes
[ 5] 1.00-2.00 sec 112 MBytes 938 Mbits/sec 144 327 KBytes
[ 5] 2.00-3.00 sec 112 MBytes 939 Mbits/sec 144 269 KBytes
[ 5] 3.00-4.00 sec 111 MBytes 929 Mbits/sec 96 320 KBytes
[ 5] 4.00-5.00 sec 113 MBytes 948 Mbits/sec 96 287 KBytes
[ 5] 5.00-6.00 sec 112 MBytes 938 Mbits/sec 96 327 KBytes
[ 5] 6.00-7.00 sec 112 MBytes 938 Mbits/sec 144 294 KBytes
[ 5] 7.00-8.00 sec 112 MBytes 940 Mbits/sec 96 362 KBytes
[ 5] 8.00-9.00 sec 112 MBytes 938 Mbits/sec 144 242 KBytes
[ 5] 9.00-10.00 sec 112 MBytes 939 Mbits/sec 96 318 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 1.10 GBytes 941 Mbits/sec 1104 sender
[ 5] 0.00-10.00 sec 1.09 GBytes 938 Mbits/sec
receiver
The retries are most likely due to the destination host being on a
different switch so the packets have to pass through two switches. When
the destination host is on the same switch, there are no retries:
[ 5] local 192.168.4.6 port 60268 connected to 192.168.4.15 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 114 MBytes 959 Mbits/sec 0 373 KBytes
[ 5] 1.00-2.00 sec 112 MBytes 939 Mbits/sec 0 392 KBytes
[ 5] 2.00-3.00 sec 112 MBytes 941 Mbits/sec 0 392 KBytes
[ 5] 3.00-4.00 sec 112 MBytes 943 Mbits/sec 0 392 KBytes
[ 5] 4.00-5.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
[ 5] 5.00-6.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
[ 5] 6.00-7.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
[ 5] 7.00-8.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
[ 5] 8.00-9.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
[ 5] 9.00-10.00 sec 112 MBytes 941 Mbits/sec 0 443 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 1.10 GBytes 943 Mbits/sec 0 sender
[ 5] 0.00-10.00 sec 1.10 GBytes 941 Mbits/sec
receiver
'ethtool -k' shows that the offload options of interest are turned on:
tcp-segmentation-offload: on
generic-segmentation-offload: on
Compare with the onboard Ethernet interface with the RTL8168evl chipset:
[ 3.015108] r8169 0000:04:00.0 eth1: RTL8168evl/8111evl,
94:de:80:21:61:12, XID 2c9, IRQ 32
tcp-segmentation-offload: off
generic-segmentation-offload: off [requested on]
iperf3 results:
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 105 MBytes 882 Mbits/sec 0 310 KBytes
[ 5] 1.00-2.00 sec 106 MBytes 886 Mbits/sec 0 1.03 MBytes
[ 5] 2.00-3.00 sec 102 MBytes 860 Mbits/sec 0 1.03 MBytes
[ 5] 3.00-4.00 sec 104 MBytes 870 Mbits/sec 0 1.03 MBytes
[ 5] 4.00-5.00 sec 104 MBytes 870 Mbits/sec 0 1.08 MBytes
[ 5] 5.00-6.00 sec 104 MBytes 870 Mbits/sec 0 1.08 MBytes
[ 5] 6.00-7.00 sec 104 MBytes 870 Mbits/sec 0 1.08 MBytes
[ 5] 7.00-8.00 sec 102 MBytes 860 Mbits/sec 0 1.08 MBytes
[ 5] 8.00-9.00 sec 104 MBytes 870 Mbits/sec 0 1.08 MBytes
[ 5] 9.00-10.00 sec 104 MBytes 870 Mbits/sec 0 1.08 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 1.01 GBytes 871 Mbits/sec 0 sender
[ 5] 0.00-10.00 sec 1.01 GBytes 868 Mbits/sec
receiver
Likewise the traffic passed through two switches, but the speed was
throttled (due I assume to the disabled offload options) so there was
adequate bandwidth for all packets to arrive in a timely way.
BTW, I've discovered that two mini-PCs I have on my LAN also have the
RTL8168evl chipset, have the same two offload parameters turned off, and
suffer from the same network transmit performance issue. I use them as
media players (MythTV front ends) and perform acceptably with high-def
video content so I'm not concerned about them.
Conclusion: a change to the r8169 module in recent Linux kernels
regressed performance with the RTL8168evl chipset.
Dave
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