Messages in this thread | | | Subject | Re: [PATCH 1/2] cpuidle : auto-promotion for cpuidle states | From | Daniel Lezcano <> | Date | Fri, 22 Mar 2019 14:26:07 +0100 |
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On 22/03/2019 10:45, Rafael J. Wysocki wrote: > On Fri, Mar 22, 2019 at 8:31 AM Abhishek Goel > <huntbag@linux.vnet.ibm.com> wrote: >> >> Currently, the cpuidle governors (menu /ladder) determine what idle state >> an idling CPU should enter into based on heuristics that depend on the >> idle history on that CPU. Given that no predictive heuristic is perfect, >> there are cases where the governor predicts a shallow idle state, hoping >> that the CPU will be busy soon. However, if no new workload is scheduled >> on that CPU in the near future, the CPU will end up in the shallow state. >> >> In case of POWER, this is problematic, when the predicted state in the >> aforementioned scenario is a lite stop state, as such lite states will >> inhibit SMT folding, thereby depriving the other threads in the core from >> using the core resources. >> >> To address this, such lite states need to be autopromoted. The cpuidle- >> core can queue timer to correspond with the residency value of the next >> available state. Thus leading to auto-promotion to a deeper idle state as >> soon as possible. > > Isn't the tick stopping avoidance sufficient for that?
I was about to ask the same :)
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