On Wed, Mar 16, 2016 at 9:05 AM, Peter Zijlstra <pet...@infradead.org> wrote: > On Tue, Mar 15, 2016 at 08:36:57PM -0700, Steve Muckle wrote: >> > Then again, maybe this knob will be part of the mythical >> > power-vs-performance slider? >> >> Patrick Bellasi's schedtune series [0] (which I think is the referenced >> mythical slider) aims to provide a more sophisticated interface for >> tuning scheduler-driven frequency selection. In addition to a global >> boost value it includes a cgroup controller as well for per-task tuning. >> >> I would definitely expect the margin/boost value to be modified at >> runtime, for example if the battery is running low, or the user wants >> 100% performance for a while, or the userspace framework wants to >> temporarily tailor the performance level for a particular set of tasks, etc. > > OK, so how about we start with it as a debug knob, and once we have > experience and feel like it is indeed a useful runtime knob, we upgrade > it to ABI. > > The problem with starting out as ABI is that its hard to take away > again.
Agreed, plus it is quite hard to get ABI right from the outset. Even if we decide on a sysfs knob, it still is unclear what exactly should be represented by it in what units etc.
