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This was created > > > explicitly for cpu controller. The proposed change blocks it > > > effectively forcing cpu controller into regular domain controller > > > behavior subject to no-internal-process rule. Note these are > > > enforced at controller granularity and this means that users who > > > use the threaded mode will be forced to pick between the two. > > > > Right... this then means we need two controls, one to do > > hierarchical bandwidth distribution, and one to assign bandwidth to > > the internal group -- which is then subject to its own bandwidth > > distribution constraint. > > > > This might be a little confusing, but there is no way around that > > AFAICT. > > Just to check if I'm following, you are thinking something like below? > > groupA/ > cpu.rt.max = "50 50 100" <- 0.5 from root > cpu.rt.internal = "20 20 100" <- 0.2 from groupA for threads at > this level > + threadA < > + threadB < > +- group1/ > cpu.rt.max = "30 30 100" <- 0.3 from groupA > + threadC > > And we still keep it flat, so 2 dl-entities (per CPU), one handles > threads at groupA level and the other threads inside group1? An alternative idea I was thinking about: we create 2 dl entities (one for "groupA" and one for "group1"); we set cpu.rt.max for groupA, and we subtract group1's utilization from it (so, if groupA's cpu.rt.max is "50 100" and group1's cpu.rt.max is "30 100", groupA is served by a dl entity (50-30,100)=(20,100) while group1 is served by a dl entity (30,100)). Basically, with this idea the "internal" reservation is automatically computed based on rt.max and on the children cgroups. A possible issue is that if the children consume all the groupA's utilization the groupA RT tasks remain with 0 runtime (and never execute). Luca