On Mon, May 23, 2016 at 11:58:49AM +0100, Morten Rasmussen wrote: > For systems with the SD_ASYM_CPUCAPACITY flag set on higher level in the > sched_domain hierarchy we need a way to enable wake-up balancing for the > lower levels as well as we may want to balance tasks that don't fit the > capacity of the previous cpu. > > We have the option of introducing a new topology flag to express this > requirement, or let the existing SD_BALANCE_WAKE flag be set by the > architecture as a topology flag. The former means introducing yet > another flag, the latter breaks the current meaning of topology flags. > None of the options are really desirable. I'd propose to replace SD_WAKE_AFFINE with SD_BALANCE_WAKE. And the SD_WAKE_AFFINE semantic is simply "waker allowed":
waker_allowed = cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); This can be implemented without current functionality change. >From there, the choice between waker and wakee, and fast path select_idle_sibling() and the rest slow path should be reworked, which I am thinking about.
