On 11/15/20 12:05 AM, Kévin Le Gouguec wrote: > Hello, > > I am running Debian Buster (XFCE) on a Dell Laptop[1] with some packages > upgraded from backports[2], notably linux-image-amd64. After upgrading > to version 5.8, I started noticing some UI "choppiness". To give a few > examples: > > - when typing (in any application, e.g. Emacs, Terminator, Firefox): at > its worst, I can type a bunch of words, sit back, wait a few seconds, > then watch the words appear letter by letter. > > - when launching programs: startup times are very inconsistent; e.g. if > I loop on > while time emacs -Q --eval '(kill-emacs)' ; do continue ; done > or > while time terminator -x "bash -c exit" ; do continue ; done > times vary between 1× and 3× what I observe on kernel 5.7 (where times > barely vary at all, ±5% at most). > > - when scrolling a PDF with Evince with the touchpad: the display > "freezes" (the pages do not seem to be scrolling) and jumps to the new > position after a few seconds; nonetheless, the pages *do* scroll > continuously, as the mouse pointer changes from an arrow to an I-beam, > presumably as text and whitespace move past it. > > Neither htop, journalctl nor dmesg report anything suspicious to my > untrained eye; the only difference I spotted was the CPU governor: on > 5.7 it is "powersave"; on 5.8 it is "ondemand". Naively cpufreq-setting > all cores to powersave on 5.8 does not make the problem go away, though. > > One curious thing is that looking at > watch -n0.5 grep MHz /proc/cpuinfo > > - on 5.7, the system is very responsive, and the idle frequency is > around 800 MHz; > - on 5.8, the system lags despite the idle frequency never going below > 1700 MHz. > > This might all be a red herring though, for all I know. I did not > immediately realize that the performance drops came from 5.8; I only > understood that after studying a bunch of other hypotheses (uninstalling > xserver-xorg-video-intel, disabling services such as speech-dispatcher > and tor), coming up short, rebooting, opening Grub's "advanced options" > and realizing that 5.7 was still on my system. > > I've since rebooted multiple times on 5.7 and 5.8, and I'm positive that > the problem only occurs with 5.8. > > > I'm not sure what to look at next. I've searched the Web for people > having performance issues with 5.8, but nothing caught my eye. > > I realize that "performance bad ☹" testimonies like this are probably > not very actionable; let me know if there's anything I can do to make > this "diagnosis" more precise. Also, I hope this is the right place for > this kind of support request; I assume it is too vague as-is for a > proper bug report… Let me know if I should post this elsewhere. > > > Thank you for your time, and sorry for the poor report. > > > [1] Dell Latitude 3190. Attached outputs from lscpu and lspci: > > > > [2] Potentially relevant backport packages: > > $ aptitude search '?narrow(?installed, ?archive(buster-backports)) > ?name(firmware~|linux~|wireless)' -F '%p' > firmware-amd-graphics > firmware-iwlwifi > firmware-linux > firmware-linux-nonfree > firmware-misc-nonfree > linux-image-5.8.0-0.bpo.2-amd64 > linux-image-amd64 > wireless-regdb > > Potentially relevant non-free packages: > > $ aptitude search '?installed ?section(non-free/) > !?name(-doc$~|^manpages-)' -F '%p' > amd64-microcode > firmware-amd-graphics > firmware-iwlwifi > firmware-linux > firmware-linux-nonfree > firmware-misc-nonfree > intel-microcode >
Hi Kévin, Linux kernel version (5.8) is old and unsupported (EOL) branch. Maybe you should wait for 5.9 to be available from backports or even 5.10 - this version will be LTS and next Debian stable version will probably use it. While waiting you can try to use 5.7 if possible. Kind regards Georgi
