given the link quality observations in #11 and the behavior in #12, it's pretty clear that the problem is with the radio power management.
since it isn't improved at all via any of the PM settings, that suggests it's simply broken rather than overly-aggressive. for reference, the head for the last good version of the driver is 6A56582B1FEECB841E329C4 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1795116 Title: large performance regression (~20-40%) in wifi with 4.15.0-33 and later Status in linux package in Ubuntu: Confirmed Bug description: 16.04 install using the HWE stack. after several weeks of uptime on -32, an update to -34 showed a major drop in wifi throughput, dependent solely on the kernel chosen: $ uname -a && ./wifibench.sh Linux brix 4.15.0-32-generic #35~16.04.1-Ubuntu SMP Fri Aug 10 21:54:34 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux Tue 25-Sep-18 06:07 PlatformSDK-SVR2003R2.iso 429,840,384 100% 8.41MB/s 0:00:48 (xfr#1, to-chk=0/1) sent 429,945,420 bytes received 35 bytes 8,685,766.77 bytes/sec $ uname -a && ./wifibench.sh Linux brix 4.15.0-34-generic #37~16.04.1-Ubuntu SMP Tue Aug 28 10:44:06 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux Tue 25-Sep-18 06:14 PlatformSDK-SVR2003R2.iso 429,840,384 100% 4.83MB/s 0:01:24 (xfr#1, to-chk=0/1) sent 429,945,420 bytes received 35 bytes 5,028,601.81 bytes/sec (the script is a simple rsync from a NAS. nothing in the NAS, or the router, or the physical positions of the devices or etc etc has changed, let alone in those 7 minutes). there is no interference, no other devices connected, etc. prior to the transfer, the link quality is 62-64 and the signal similarly weaker because of power saving, but once packets are in flight it looks perfect: $ iwconfig wlan0 IEEE 802.11 ESSID:"****" Mode:Managed Frequency:2.452 GHz Access Point: **** 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=70/70 Signal level=10 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:15 Missed beacon:0 the client is a J1900-based (baytrail) machine with a RTL8723BE wifi module. average performance while on -32 was consistently 70-80 Mb/s, over a period of several weeks. with -33 and later, it's generally 50-65. (that machine has no access to launchpad. i'll try apport-cli over the weekend). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1795116/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
