Am Thu, 2 Aug 2018 18:22:02 +0200 schrieb Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>: > 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. I am using 4.16 as well, just did not find the patch online to provide a better link. > > 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. I already reverted the patch on my side and did some testing. That compiled when i wrote the first mail ;). If nobody sees a reason to keep the restriction, it should be removed. Henning > > 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
