On Tue, 8 Nov 2016 17:51:33 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > You really should already know this. I know what we want to do, but there's some momentous problems that need to be solved first. Until then, we may be forced to continue with hacks. > > As stands the current rt cgroup code (and all this throttling code) is a > giant mess (as in, its not actually correct from a RT pov). We should > not make it worse by adding random hacks to it. > > The right way to to about doing this is by replacing it with something > better; like the proposed DL server for FIFO tasks -- which is entirely > non-trivial as well, see existing discussion on that. Right. The biggest issue that I see is how to assign affinities to FIFO tasks and use a DL server to keep them from starving other tasks? > > I'm not entirely sure what this patch was supposed to fix, but it could > be running CFS tasks with higher priority than RT for a window, instead I'm a bit confused with the above sentence. Do you mean that this patch causes CFS tasks to run for a period with a higher priority than RT? Well, currently we have the both CFS tasks and the "idle" task run higher than RT, but this patch changes that to be just CFS tasks. > of throttling RT tasks. This seems fairly ill specified, but something > like that could easily done with an explicit or slack time DL server for > CFS tasks. If we can have a DL scheduler that can handle arbitrary affinities, then all could be solved with that. -- Steve -- 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
