Hello, On Mon, Sep 21, 2020 at 11:21:54AM +0200, Daniel Vetter wrote: > The part I don't like about this is that it all feels rather hacked > together, and if we add more stuff (or there's some different thing in the > system that also needs rt scheduling) then it doesn't compose. > > So question to rt/worker folks: What's the best way to let userspace set > the scheduling mode and priorities of things the kernel does on its > behalf? Surely we're not the first ones where if userspace runs with some > rt priority it'll starve out the kernel workers that it needs. Hardcoding > something behind a subsystem ioctl (which just means every time userspace > changes what it does, we need a new such flag or mode) can't be the right > thing. Maybe not first but there haven't been many. The main benefit of workqueue is that the users get to pool the worker threads automatically. I don't think the existing workqueue design is something suitable for actual RT use cases. Furthermore, there are inherent conflicts between sharing resources and RT as this this patchset is already showing w/ needing per-crtc worker thread. Maybe we can further abstract it if there are more use cases but for now kthread_worker based implementation sounds about right to me. Thanks. -- tejun
