On Sat, May 20, 2023 at 06:14:17PM -0500, Justin Forbes wrote: > On Sat, May 20, 2023 at 3:44 PM Demi Marie Obenour > <demiobenour@xxxxxxxxx> wrote: > > > > I noticed that by default, Qubes OS has voluntary kernel preemption > > as opposed to full preemption. I found that enabling full preemption > > (preempt=full on kernel command line) makes the system significantly > > more responsive under heavy I/O load. In particular, if I build a > > kernel in a Qubes OS VM, it significantly degrades responsiveness > > without preempt=full. With preempt=full, the system remains > > responsive. The storage stack used is LVM thin provisioning on LUKS, > > and I have observed significant CPU usage in dom0 kernel threads with > > names that indicate they are related to dm-thin and dm-crypt. > > > For workstation, preempt=full does likely make sense, and I have been > running it for a while. For server, maybe not so much. That is the > joy of dynamic preempt. You can boot with preempt=full and run that > way if you like. There is an open issue for the workstation WG to > look at making preempt=full the default there at some point. What's the downside from full pre-empt that makes it inappropriate as the defualt for Fedora server spins too ? Is it that it is trading off overall peak performance in favour of reduced latency, and we think servers would prefer the peak performance in general ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :| _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
