On Wed, 2018-05-02 at 05:44 +0000, Pkshih wrote: > > > -----Original Message----- > > From: João Paulo Rechi Vita [mailto:jprv...@gmail.com] > > Sent: Wednesday, May 02, 2018 6:41 AM > > To: Larry Finger > > Cc: Steve deRosier; 莊彥宣; Pkshih; Birming Chiu; Shaofu; Steven Ting; > > Chaoming_Li; Kalle Valo; > > linux-wireless; Network Development; LKML; Daniel Drake; João Paulo Rechi > > Vita; linux@endlessm.c > om > > Subject: Re: RTL8723BE performance regression > > > > On Tue, Apr 3, 2018 at 7:51 PM, Larry Finger <larry.fin...@lwfinger.net> > > wrote: > > > On 04/03/2018 09:37 PM, João Paulo Rechi Vita wrote: > > >> > > >> On Tue, Apr 3, 2018 at 7:28 PM, Larry Finger <larry.fin...@lwfinger.net> > > >> wrote: > > >> > > >> (...) > > >> > > >>> 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? > > >> > > >> > > >> Yes, that is why I've been passing ant_sel=1 during my tests -- this > > >> was needed to achieve a good performance in the past, before this > > >> regression. I've also opened the laptop chassis and confirmed the > > >> antenna cable is plugged to the connector labeled with "1" on the > > >> card. > > >> > > >>> 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. > > >>> > > >> > > >> What is the recommended way to monitor the signal strength? > > > > > > > > > The btcoex code is developed for multiple platforms by a different group > > > than the Linux driver. I think they made a change that caused ant_sel to > > > switch from 1 to 2. At least numerous comments at > > > github.com/lwfinger/rtlwifi_new claimed they needed to make that change. > > > > > > Mhy recommended method is to verify the wifi device name with "iw dev". > > > Then > > > using that device > > > > > > sudo iw dev <dev_name> scan | egrep "SSID|signal" > > > > > > > I have confirmed that the performance regression is indeed tied to > > signal strength: on the good cases signal was between -16 and -8 dBm, > > whereas in bad cases signal was always between -50 to - 40 dBm. I've > > also switched to testing bandwidth in controlled LAN environment using > > iperf3, as suggested by Steve deRosier, with the DUT being the only > > machine connected to the 2.4 GHz radio and the machine running the > > iperf3 server connected via ethernet. > > > > We have new experimental results in commit af8a41cccf8f46 ("rtlwifi: cleanup > 8723be ant_sel definition"). You can use the above commit and do the same > experiments (with ant_sel=0, 1 and 2) in your side, and then share your > results. > Since performance is tied to signal strength, you can only share signal > strength. >
Please pay attention to cold reboot once ant_sel is changed.
