Thanks for the info Lukas; much appreciated. As a side note for this would it be useful to denote which versions of systemd the page https://www.freedesktop.org/wiki/Software/systemd/MyServiceCantGetRealtime/ is valid for? That page cost me a fair amount of time trying to apply the solutions and trying to work out what I was doing wrong before I managed to find the information about those options not being applicable anymore
Thanks Jon On Fri, 8 Nov 2019 at 10:24, Lukas Nykryn <lnyk...@redhat.com> wrote: > Hi! > > I think you should contact the Red Hat support with this question. Most of > the distribution have CONFIG_RT_GROUP_SCHED disabled since in the general > use cases people don't use it at all. RHEL is an exception here, since we > keep that feature on, despite the recommendation of upstream, to cover some > weird use-cases. > > You also might want to look at https://access.redhat.com/articles/3696121 > > Lukas > > > > čt 7. 11. 2019 v 18:15 odesílatel Jon Sykes <jono.syke...@gmail.com> > napsal: > >> Hi, >> >> I'm using RHEL7 with systemd-219-62.el7_6.6.x86_64. I've recently hit an >> issue whereby a process started by a systemd service cannot assign itself >> realtime priority. Digging into the issue it seems that it is because >> systemd starts all services within a cpu/system.slice/<service_name> cgroup >> which by default wont be allocated any rt runtime through >> the cpu.rt_runtime_us value. >> >> I searched for info on how to solve this issue and came across >> https://www.freedesktop.org/wiki/Software/systemd/MyServiceCantGetRealtime/ >> unfortunately >> 2 of the 3 suggestions don't seem to be valid anymore: >> >> - /etc/systemd/system.conf and set DefaultControllers= >> This appears to have been removed as an option. When I tried this it had >> no effect >> >> - edit your service file, and add ControlGroup=cpu:/ to its [Service] >> section >> This doesn't appear to be a valid option anymore: >> https://bugzilla.redhat.com/show_bug.cgi?id=999986 >> >> This only leaves the option of setting cpu.rt_runtime_us value for the >> unit, however, there are a number of reasons why this isn't ideal and if >> the root cgroup config changes at any point then the value I choose isn't >> guaranteed to do what I had intended. (as pointed out in: >> https://lists.freedesktop.org/archives/systemd-devel/2015-March/029144.html >> ) >> >> Is there any other way to get my service to run within a cgroup that >> allows it to assign itself realtime priority? It would seem preferable to >> be able to just run the service in the root cgroup - is this possible >> through configuration? >> >> Thanks >> Jon >> _______________________________________________ >> systemd-devel mailing list >> systemd-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/systemd-devel > >
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