Re: [RFC] sched: low latency feedback to userspace

2016-05-09 Thread Peter Zijlstra
On Mon, May 09, 2016 at 03:03:59PM +0200, Maximilian Krüger wrote: > > >sched_yield() for anything other than SCHED_FIFO / SCHED_DEADLINE is a > >'bug'. That is, calling sched_yield() outside of those two cases is > >undefined behaviour and the kernel is free to eat your granny and set your > >pet

Re: [RFC] sched: low latency feedback to userspace

2016-05-09 Thread Maximilian Krüger
sched_yield() for anything other than SCHED_FIFO / SCHED_DEADLINE is a 'bug'. That is, calling sched_yield() outside of those two cases is undefined behaviour and the kernel is free to eat your granny and set your pet on fire. okay, fair.c/yield_task_fair() does not exactly sound, as if it

Re: [RFC] sched: low latency feedback to userspace

2016-05-09 Thread Peter Zijlstra
On Mon, May 09, 2016 at 12:18:54PM +0200, Maximilian Krüger wrote: > I am planning to extend the CFS as part of my master thesis. I want > user-threads to allow to decide whether to enter a critical section or call > sched_yield() sched_yield() for anything other than SCHED_FIFO / SCHED_DEADLINE i

[RFC] sched: low latency feedback to userspace

2016-05-09 Thread Maximilian Krüger
I am planning to extend the CFS as part of my master thesis. I want user-threads to allow to decide whether to enter a critical section or call sched_yield() For tight synchronized workloads it might be useful, to only start certain short tasks, when they still can be completed in the current t