On Sun, Jan 22, 2017 at 09:31:44AM +0800, Alex Shi wrote: > > >Yeah, that could be problematic. The code snippet gives the general idea but > >it > >could be changed by for example by a flag telling the cpus when they enter > >idle > >to update their state_count. Or something like that. > > Yes, this idea could be helpful. > > But since the idle path isn't a hot path. and a few memory access won't cost > a lot. So I doubt if the benefit could be measurable.
It won't be measurable, as well as reading the cpu device latency before checking the latency req is zero, but it makes sense. The idle routine is not a hot path but a very special place where the interrupt are disabled, the rcu is not usable, tick is disabled etc ... Perhaps it is not a problem for the moment, but it is probably worth to mention that using API from other subsystems in the idle select path could be problematic and perhaps it is time to think about another approach for the future. -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog
