On 2017.11.16 08:11 Thomas Ilsche wrote: > On 2017-11-09 08:38, Len Brown wrote: >> From: Len Brown <len.br...@intel.com> >> >> While there are several mechanisms (cmdline, sysfs, PM_QOS) to limit >> cpuidle to shallow idle states, there is no simple mechanism >> to give the hardware permission to enter the deeptest state permitted by >> PM_QOS. >> >> Here we create the "cpuidle.use_deepest" modparam to provide this capability. >> >> "cpuidle.use_deepest=Y" can be set at boot-time, and >> /sys/module/cpuidle/use_deepest can be modified (with Y/N) at run-time. > > This is a good option to have and can conveniently prevent idle power > consumption > issues. But that wouldn't be a reasonable default, would it? > I still think there is an inherent need for a heuristic and a corresponding > mitigation to avoid staying in a sleep state too long.
I think so, yes. The potential energy savings, depending on work flow, are significant. For the idle state 0 case, I have some supporting data that I will send on the other e-mail thread. ... Doug
