the machine is usually ~20 feet away from the router, through multiple walls and a floor. i moved it last night so it was 6 feet away with LOS, and the results from that are very interesting:
Linux brix 4.15.0-36-generic #39~16.04.1-Ubuntu SMP Tue Sep 25 08:59:23 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux Current Frequency:2.452 GHz (Channel 9) Link Quality=70/70 Signal level=-30 dBm Sat 20-Oct-18 17:23 429,840,384 100% 10.91MB/s 0:00:37 (xfr#1, to-chk=0/1) sent 429,945,420 bytes received 35 bytes 11,167,414.42 bytes/sec and under the same ideal conditions: 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 Current Frequency:2.452 GHz (Channel 9) Link Quality=70/70 Signal level=-32 dBm Sat 20-Oct-18 17:29 429,840,384 100% 9.10MB/s 0:00:45 (xfr#1, to-chk=0/1) sent 429,945,420 bytes received 35 bytes 9,449,350.66 bytes/sec so the newer kernel is MUCH better in that situation, whereas the old kernel essentially performs exactly the same. the machine has a fairly weak cpu, and basically has one core pegged with iowait during these transfers, so optimisations (either in general for meltdown etc, or the stack, or in the driver specifically) could certainly account for that sort of speedup. however, that only further highlights just how bad this regression is, because the driver is now nearly 20% faster in the abstract but still massively slower at range despite all that improvement. it also explains why nobody would notice the regression during development. i'm happy to test proposed fixes or provide more information, but i don't think there's anything more i can do at my end until somebody else steps in. @joseph - do you have a tracking reference for upstream yet? TIA -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1795116 Title: large performance regression (~20-40%) in wifi with 4.15.0-33 and later To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1795116/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs