On Sun, 2015-10-04 at 22:29 +1100, Basil Chupin wrote:
Further discussion in this thread shows that people may notice the difference in performance because of this change - so, for Chrissake, why make the change? Leave the CONFIG_HZ=1000 alone.
We decided to leave PREEMPT alone, because that really will make a difference for some. Tick frequency is another matter entirely. Tick frequency was a major factor in the old O(1) scheduler, as that determined scheduling granularity given competing tasks of equal priority, but that has not been the case for a very long time. CFS does not necessarily context switch upon every timer interrupt. It will do some bean counting, will add a bit of overhead, and may context switch, but the vast majority of the time, preemption is wakeup driven. Fact is that we chew up quite a pile of cycles _over_ scheduling in PREEMPT kernels in the general case. If you want something to fret over, fret over those very real squandered joules :) -Mike -- To unsubscribe, e-mail: opensuse-kernel+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-kernel+owner@opensuse.org