On Mon, 2018-05-07 at 14:49 -0700, João Paulo Rechi Vita wrote: > On Tue, May 1, 2018 at 10:58 PM, Pkshih <pkshih@xxxxxxxxxxx> wrote: > > On Wed, 2018-05-02 at 05:44 +0000, Pkshih wrote: > >> > >> > -----Original Message----- > >> > From: João Paulo Rechi Vita [mailto:jprvita@xxxxxxxxx] > >> > 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@endless > m.c > >> om > >> > Subject: Re: RTL8723BE performance regression > >> > > >> > On Tue, Apr 3, 2018 at 7:51 PM, Larry Finger <Larry.Finger@xxxxxxxxxxxx> 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.Finger@xxxxxxxxxxxx> > >> > >> 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. > > > > I've tested the commit mentioned above and it fixes the problem on top > of v4.16 (in addition to the latest wireless-drivers-next also been > fixed as it already contains such commit). On v4.15, we also need the > following commits before "af8a41cccf8f rtlwifi: cleanup 8723be ant_sel > definition" to have a good performance again: > > 874e837d67d0 rtlwifi: fill FW version and subversion > a44709bba70f rtlwifi: btcoex: Add power_on_setting routine > 40d9dd4f1c5d rtlwifi: btcoex: Remove global variables from btcoex v4.15 isn't longterm version and had been EOL. > > Surprisingly, it seems forcing ant_sel=1 is not needed anymore on > these machines, as the shown by the numbers bellow (ant_sel=0 means > that actually no parameter was passed to the module). I have powered > off the machine and done a cold boot for every test. It seems > something have changed in the antenna auto-selection code since v4.11, > the latest point where I could confirm we definitely need to force > ant_sel=1. I've been trying to understand what causes this difference, > but haven't made progress on that so far, so any suggestions are > appreciated (we are trying to decide if we can confidently drop the > downstream DMI quirks for these specific machines). > I think your rtl8723be module programed correct efuse content, so it works properly with ant_sel=0, and quirk isn't required for your machine. > w-d-n ant_sel=0: -14.00 dBm, 69.5 Mbps -> good > w-d-n ant_sel=1: -10.00 dBm, 41.1 Mbps -> good > w-d-n ant_sel=2: -44.00 dBm, 607 kbps -> bad > > v4.16 ant_sel=0: -12.00 dBm, 63.0 Mbps -> good > v4.16 ant_sel=1: - 8.00 dBm, 69.0 Mbps -> good > v4.16 ant_sel=2: -50.00 dBm, 224 kbps -> bad > > v4.15 ant_sel=0: - 8.00 dBm, 33.0 Mbps -> good > v4.15 ant_sel=1: -10.00 dBm, 38.1 Mbps -> good > v4.15 ant_sel=2: -48.00 dBm, 206 kbps -> bad > With your results, the efuse content is programmed as one or two antenna on AUX path. Regards, PK
