On 2018.03.19 05:47 Thomas Ilsche wrote: > On 2018-03-15 23:19, Rafael J. Wysocki wrote: >> From: Rafael J. Wysocki <[email protected]> >> >> If the scheduler tick has been stopped already and the governor >> selects a shallow idle state, the CPU can spend a long time in that >> state if the selection is based on an inaccurate prediction of idle >> time. That effect turns out to be noticeable, so it needs to be >> mitigated. > > What are some common causes for that situation? > How could I trigger this for testing?
It appeared quite readily with my simple 100% load on one CPU test. Back then (V3) there only 6 patches in the set, and before the re-spin there ended up being a patch 7 of 6, which made a significant difference in both package power and the histograms of times in each idle state. Reference: https://marc.info/?l=linux-pm&m=152075419526696&w=2 ... Doug
