I begin to find a way that help me investigate fifo: SCHED_ERROR 0a [CTXSW_TIMEOUT] errors. See https://gitlab.freedesktop.org/xorg/driver/xf86-video-nouveau/-/issues/339 I believe this affects mostly Fermi, Kepler and Maxwell1 graphic cards. I'd like first to describe a bit how I proceed, then talk about separating this issue in many. I am working on Gnome Debian Testing. This environment react well (no freeze) when programs or XWayland are killed from the error. I am using drm-misc, from: https://cgit.freedesktop.org/drm-misc/tree/ that I got with git clone git://cgit.freedesktop.org/drm-misc/tree/ and have compiled. my kernel command line in /etc/grub/default have: GRUB_CMDLINE_LINUX="pcie_aspm=off nouveau.debug=info nouveau.noaccel=0 drm.debug=0 log_buf_len=8M" Not sure if only me need pcie_aspm=off to remove some AER errors on PCIe bus. The first thing I do is: su - the - allows to have access to programs in /usr/sbin dmesg --console-off because I will generate a lot of messages, and I want them only in log files, not on console screen. I launch Firefox, most of the bugs I get by browsing the web. When ready to debug I do: echo 255 > /sys/module/drm/parameters/debug [At first was using 2, then 1 as suggested by /usr/sbin/modinfo drm, but then concluded 255 for all is the best to have all the cases that could cause the timeout] I browse the web. When Firefox stop, or everything goes away and return to the gdm (login screen), first thing I do is: echo 0 > /sys/modules/drm/parameters/debug to stop logging so much messages. Then I do: journalctl -b -g SCHED to find at which second, the CTXSW_TIMEOUT message is. Suppose it is at 08:21:14. journalctl -b --since 08:21:13 --until 08:21:14 until the CTXSW_TIMEOUT is not the first line, I do it again with minus 1 sec on --since Let's say I get up to: 08:21:09: journalctl -b --since 08:21:09 --until 08:21:14 -o short-monotone > err.txt cp err.txt /home/paul mv /home/paul/err.txt /home/paul/journalctl_no1.txt chown paul:paul /home/paul/journalctl_no1.txt And then, as normal user paul: gnome-text-editor journalctl_no1.txt & and I search for: SCHED again... and I looks the lines before to try to figure out the cause of the timeout. If you take a look at: See https://gitlab.freedesktop.org/xorg/driver/xf86-video-nouveau/-/issues/339 you can see that what is before vary quite a bit each time. I suspect there is many causes that can result in a MMU error on the GPU and so cause a timeout. There is the possibility of a non-related memory corruption... I suppose. But if not, it would make some sense to open a different issue for each different things happening before the timeout message. Not sure, if is is really the good thing to do. So in part why I am writing this message to ask opinion(s).
