On 5/6/21 8:33 AM, Hao Xu wrote: > Users may want a higher priority for sq_thread or io-worker. Provide a > way to change the nice value(for SCHED_NORMAL) or scheduling policy. Silly question - why is this needed for sqpoll? With the threads now being essentially user threads, why can't we just modify nice and scheduler class from userspace instead? That should work now. I think this is especially true for sqpoll where it's persistent, and argument could be made for the io-wq worker threads that we'd need io_uring support for that, as they come and go and there's no reliable way to find and tweak the thread scheduler settings for that particular use case. It may be more convenient to support this through io_uring, and that is a valid argument. I do think that the better way would then be to simply pass back the sqpoll pid after ring setup, because then it'd almost be as simple to do it from the app itself using the regular system call interfaces for that. In summary, I do think this _may_ make sense for the worker threads, being able to pass in this information and have io-wq worker thread setup perform the necessary tweaks when a thread is created, but it does seem a bit silly to add this for sqpoll where it could just as easily be achieved from the application itself without needing to add this support. What do you think? -- Jens Axboe
