Lazy Preemption Merged Along With Other Scheduler Improvements For Linux 6.13

[waxhead]

EEVDF doesn't by itself cause any more or less context switches than any other scheduler....

....Now it may be that these choices about which process to run leads to more context switches, if EEVDF more often selects some process that uses a tiny amount of CPU then goes to sleep again...

Thanks for the answer, but this is exactly my point and why I asked about how the lazy patch potentially might trigger this condition (which I **assume** would not be the case with CFS to the same extent).

Not sure how much a context switch "cost" these days, or if this time cost is part of the lag calculation in EEVDF somehow, but I can imagine it won't matter much unless the CPU is fully loaded anyway, but it is still interesting.

[Mitch]

EEVDF doesn't by itself cause any more or less context switches than any other scheduler. A better scheduler can just do a better job of selecting which task to run next (well, ignoring things like moving tasks over to another cpu etc. which would cause an interrupt (IPI) and thus a potential preemption on that CPU etc.). I think the main advantage of EEVDF over CFS is just that it's better at choosing the next task, leading to less stutter because things like pipewire or whatever is responsible for moving the cursor on the screen etc. gets access to the cpu more regularly.

Now it may be that these choices about which process to run leads to more context switches, if EEVDF more often selects some process that uses a tiny amount of CPU then goes to sleep again (like updating the mouse cursor position on the screen etc.), necessitating the scheduler to run again to select something else.

So if I understand correctly, a kernel with EEVDF and Lazy PreEmption ought have a net effect of less stuttering and latency of things like audio, UI, especially under more conditions, such as high load and reduced operating speeds (low powered devices).