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:
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[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