Messages in this thread | | | Date | Tue, 8 Nov 2016 12:17:10 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] sched/rt: RT_RUNTIME_GREED sched feature |
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On Tue, 8 Nov 2016 17:51:33 +0100 Peter Zijlstra <peterz@infradead.org> 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
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