On 2023-12-30 19:43, Martin Husemann wrote:
On Sat, Dec 30, 2023 at 06:25:29PM +0000, Jonathan Stone wrote:You can only do tickless if you can track how much time is elapsing when no ticks fire, or none are pending. I don't see how to do that without a high-res timer like a CPU cycle counter, or I/O bus cycle counter, or what-have-you. Gong fully tickless would therefore end support for machines without such a timer. Is NetBSD ready to do that?Kernels on that machines just would not run fully tickless.
Right. There is no reason to assume that all platforms would have to go tickless just because it becomes a possibility. However, I also am not sure how much value tickless adds here. The main reason I know of for tickless systems is power consumption. Not having to wake up just to count time can make a big difference. Sure, you can get higher precision for some scheduling with tickless, but I'm not sure it generally makes any actual significant difference. Being able to measure time with high precision is desierable, but we can already do that without being tickless.
Johnny
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