On Tue, May 8, 2018 at 1:37 AM, Pkshih <pkshih@xxxxxxxxxxx> wrote: > 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. > Right, but this is a performace regression in comparison to v4.11, so if "af8a41cccf8f rtlwifi: cleanup 8723be ant_sel definition" is marked for stable, shouldn't these other patches be brought as well? All releases since v4.11 are probably affected, but honestly I don't have a strong understanding of how the stable trees operate in situations like this. >> >> 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. > With v4.11 I had good performance results on this very same machine (thus same efuse contents) only when passing ant_sel=1, so there has to be some change on the code that parses the efuse contents and decides which antenna will be used. -- João Paulo Rechi Vita http://about.me/jprvita
