Had the affected machine in here (i.e. "where the router is") for other
reasons, so I was able to check those conditions too. As expected, it's
a power / antenna / etc issue:
Linux 5.3.0-19-generic #20-Ubuntu SMP Fri Oct 18 09:04:39 UTC 2019 x86_64
Fri 08-Nov-19 03:29
sent 459,277,171 bytes received 35 bytes 7,467,922.05 bytes/sec
iwlist scan, WHILE the rsync was running (so it shouldn't be power-saving at
all) with the router 6' away with clear LOS showed:
Frequency:2.422 GHz (Channel 3)
Quality=62/70 Signal level=-48 dBm
Looking at 1795116, I used to get 70/70 at -32 dBm upstairs and through half a
dozen walls, so obviously this is a significant drop in link quality given the
hugely better conditions.
Compared to 4.15.0-36 - which, bear in mind was one of the BROKEN kernels, the
performance is 7,467,922 / 11,167,414, or 66.9% of what it should be in that
scenario.
The good news is, that difference suggests it's at least not a simple
merge regression of 1795116. The bad news is, of course, that it'll need
a new round of investigation track down.
As I've said, I'm willing to set things up to help out, but I'm still
waiting for you to provide me with the ACTUAL Ubuntu kernel tree to
bisect against. In the meantime, I'll probaby try a couple of the
mainline builds since I can just dpkg those, but with no way to map the
working Ubuntu ones to the mainline tree I'll never have a baseline to
compare against in case something stupid has happened like one of the
antenna connectors has become disconnected or etc.
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You received this bug notification because you are a member of Kernel
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https://bugs.launchpad.net/bugs/1847892
Title:
large performance regression (~30-40%) in wifi with 19.10 / 5.3 kernel
Status in linux package in Ubuntu:
Confirmed
Bug description:
Probably relevant:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1795116
Card is an RTL8723BE.
On 16.04 with the HWE stack, after 1795116 was fixed performance was a
stable 75-80Mb/s.
Linux 4.15.0-55-generic #60~16.04.2-Ubuntu SMP Thu Jul 4 09:03:09 UTC 2019
x86_64
Fri 26-Jul-19 12:28
sent 459,277,171 bytes received 35 bytes 9,278,327.39 bytes/sec
Linux 4.15.0-55-generic #60~16.04.2-Ubuntu SMP Thu Jul 4 09:03:09 UTC 2019
x86_64
Sat 27-Jul-19 01:23
sent 459,277,171 bytes received 35 bytes 10,320,836.09 bytes/sec
On 18.04, performance was still a stable 75-80Mb/s.
After updating to 19.10, performance is typically ~50Mb/s, or about a
37% regression.
$ iwconfig wlan0
wlan0 IEEE 802.11 ESSID:"**"
Mode:Managed Frequency:2.442 GHz Access Point: 4C:60:DE:FB:A8:AB
Bit Rate=150 Mb/s Tx-Power=20 dBm
Retry short limit:7 RTS thr=2347 B Fragment thr:off
Power Management:on
Link Quality=59/70 Signal level=-51 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:315 Missed beacon:0
$ ./wifibench.sh
Linux 5.3.0-13-generic #14-Ubuntu SMP Tue Sep 24 02:46:08 UTC 2019 x86_64
Sat 12-Oct-19 20:30
sent 459,277,171 bytes received 35 bytes 5,566,996.44 bytes/sec
$ iwconfig wlan0
wlan0 IEEE 802.11 ESSID:"**"
Mode:Managed Frequency:2.442 GHz Access Point: 4C:60:DE:FB:A8:AB
Bit Rate=150 Mb/s Tx-Power=20 dBm
Retry short limit:7 RTS thr=2347 B Fragment thr:off
Power Management:on
Link Quality=68/70 Signal level=-42 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:315 Missed beacon:0
So no corrupted packets or etc during that transfer.
$ ifconfig wlan0
wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.33 netmask 255.255.255.0 broadcast 192.168.1.255
ether dc:85:de:e4:17:a3 txqueuelen 1000 (Ethernet)
RX packets 56608204 bytes 79066485957 (79.0 GB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 21634510 bytes 8726094217 (8.7 GB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
No issues of any kind in the week that it's been up. Just terrible
performance.
I'm painfully aware of all the module's parameters etc, and have tried
them all, with no change in the results outside of typical wifi
variance.
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