Getting maximum mileage out of tickless

Now that the tickless(/dynticks) infrastructure is integrated into the base kernel, this paper talks about various add on changes that makes tickless kernels more effective.

Tickless kernel pose some hardware challenges that were primarily exposed by the requirement of continuously running per-CPU timer. We will discuss how this issue was resolved by using HPET in a new mode. Eliminating idle periodic ticks causes kernel process scheduler not do idle balance as frequently as it would do otherwise. We provide insight into how this tricky issue of saving power with minimal impact on performance, is resolved in tickless kernel.

We will also look at the kernel and user level daemons and drivers, polling for things with their own timers and its side effect on overall system idle time, with suggestions on how to make these daemons and drivers tickless-friendly.


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