Hello, Frederic. > > Although who knows, may be some periodic file operation while idle are specific > to Android. I'll try to trace lazy callbacks while idle and the number of grace > periods associated. > > Everything related to lazy call-backs is about not waking "nocb" kthreads in order to offload one or i should say few callbacks because it is more or less useless. Currently if incoming callback is the only one, it will kick a GP whereas a GP will kick nocb_kthread to offload. In "light" loaded test cases, especially where a power drain is a key thing, such light load may lead to some kind of "noise" produced by the RCU core, i.e. kicking idle CPUs, thus wasting power. On our ARM devices it is not painful, but there is a small power gain and it is visible. For other systems, like Joel measures for Intel SoC it is more visible, because of a power cost getting in/out of isle states. This is what i see on my setup. -- Uladzislau Rezki
