On 2018-08-01 14:52:38 [+0200], Henning Schild wrote: > Hi, Hi, > i just wanted to have a look at RT_GROUP_SCHED as a way to prevent > crashing real-time applications from starving other rt application, in > the case of prio based scheduling. > I had to find out that the feature is not compatible with PREEMPT_RT > and quickly traced it down to the following commit: > > "sched: Disable CONFIG_RT_GROUP_SCHED on RT" > > https://kernel.googlesource.com/pub/scm/linux/kernel/git/paulg/3.4-rt-patches/+/1b19454df58db731fa9ca09b34909d28d4eef968/patches/0133-sched-Disable-CONFIG_RT_GROUP_SCHED-on-RT.patch please use one of the two git trees in git.kernel.org if you refer to RT patches: https://git.kernel.org/pub/scm/linux/kernel/git/rt/ Also, the v3.4 is very old and unsupported. > My current theory is that there never was a problem with the two not > being compatible ... it was more likely a broken userland, more > specific a broken cgroups setup. > Further my theory is, if you set cgroups up correctly both featues can > most likely be combined without a problem ... > But maybe i am totally wrong and there are some reasons, in that case > the commit should be a little more verbose. And i would be happy to > hear about it. As far as I recall, that test case on that FC setup was the reason to disable it. > On newer systems ... systemd is the reason ... fits the "works in ssh > but not in rc.local" So I have here v4.16.18-rt11 RT with RT_GROUP_SCHED enabled and I can't reproduce the issue anymore on Debian Sid with systemd 238. So either it does not setup the cgroups the same way it did (or FC still does) or the issue has been fixed in the meantime. Can you please test if this works as expected? I would be happy to revert the patch if there are no problems with it anymore. > regards, > Henning Sebastian -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
