On 04/03/2018 08:51 PM, João Paulo Rechi Vita wrote:
Hello, I've been trying to track a performance regression on the RTL8723BE WiFi adapter, which mainly affects the upload bandwidth (although we can see a decreased download performance as well, the effect on upload is more drastic). This was first reported by users after upgrading from our 4.11-based kernel to our 4.13-based kernel, but also confirmed to affect our development branch (4.15-based kernel) and wireless-drivers-next at the wireless-drivers-next-for-davem-2018-03-29 tag. This is happening on an HP laptop that needs rtl8723be.ant_sel=1 (and all the following tests have been made with that param). My first bisect attempt pointed me to the following commit: bcd37f4a0831 rtlwifi: btcoex: 23b 2ant: let bt transmit when hw initialisation done Which I later found to be already fixed by a33fcba6ec01 rtlwifi: btcoexist: Fix breakage of ant_sel for rtl8723be. That fix is already included in v4.15 though (and our dev branch as well), so I did a second bisect, now cherry-picking a33fcba6ec01 at every step, and it pointed me to the following commit: 7937f02d1953 rtlwifi: btcoex: hook external functions for newer chips Reverting that commit on top of our development branch fixes the problem, but on top of v4.15 I get mixed results: a few times getting a good upload performance (~5-6Mbps) but most of the time just getting ~1-1.5Mpbs (which is still better than the 0.0 then test failure I've gotten on most bad points of the bisect). Bisecting the downstream patches we carry on top of v4.15 (we base our kernel on Ubuntu's, so there are quite a few downstream changes) did not bring any clarity, as at all bisect points (plus reverting 7937f02d1953) the performance was good, so probably there was some other difference in the resulting kernels from my initial revert of that patch on top of v4.15 and each step during the bisect. I've experimented a bit with fwlps=0, but it did not bring any conclusive results either. I'll try to look at other things that may have changed (configuration perhaps?), but I don't have a clear plan yet. Have you seen anything similar, or have any other ideas or suggestions to track this problem? Even without crystal clear results, it looks like 7937f02d1953 is having a negative impact on the RTL8723BE performance, so perhaps it is worth reverting it and reworking it a later point? This are the results (testing with speedtest.net) I got at some key points: Version Commit Ping Down Up v4.11 a351e9b 12 25.44 5.99 v4.11 a351e9b 131 17.02 5.89 v4.13 569dbb8 174 14.08 0.00 v4.13 569dbb8 261 8.41 0.00 v4.15+revert d8a5b80 19 23.86 1.41 v4.15+revert d8a5b80 189 18.69 1.39
As the antenna selection code changes affected your first bisection, do you have one of those HP laptops with only one antenna and the incorrect coding in the FUSE? If so, please make sure that you still have the same signal strength for good and bad cases. I have tried to keep the driver and the btcoex code in sync, but there may be some combinations of antenna configuration and FUSE contents that cause the code to fail.
Larry
