> > So both of you are working on top of my 2 patches that deal with the > > fairness issue, but I had the feeling Tim's alternative patches[1] are > > simpler than mine and achieves the same result(after the force idle tag > > I think Julien's result show that my patches did not do as well as > your patches for fairness. Aubrey did some other testing with the same > conclusion. So I think keeping the forced idle time balanced is not > enough for maintaining fairness. > There are two main issues - vruntime comparison issue and the forced idle issue. coresched_idle thread patch is addressing the forced idle issue as scheduler is no longer overloading idle thread for forcing idle. If I understand correctly, Tim's patch also tries to fix the forced idle issue. On top of fixing forced idle issue, we also need to fix that vruntime comparison issue and I think thats where Aaron's patch helps.
I think comparing parent's runtime also will have issues once the task group has a lot more threads with different running patterns. One example is a task group with lot of active threads and a thread with fairly less activity. So when this less active thread is competing with a thread in another group, there is a chance that it loses continuously for a while until the other group catches up on its vruntime. As discussed during LPC, probably start thinking along the lines of global vruntime or core wide vruntime to fix the vruntime comparison issue? Thanks, Vineeth