On Friday 23 Mar 2018 at 16:00:59 (+0000), Morten Rasmussen wrote: > On Thu, Mar 22, 2018 at 09:27:43AM -0700, Joel Fernandes wrote: > > Hi, > > > > On Tue, Mar 20, 2018 at 2:43 AM, Dietmar Eggemann > > <dietmar.eggem...@arm.com> wrote:
[...] > > Is it possible that before the wakeup, the task's affinity is changed > > so that p->cpus_allowed no longer contains prev_cpu ? In that case > > prev_energy wouldn't matter since previous CPU is no longer an option? > > It is possible to wake-up with a disallowed prev_cpu. In fact > select_idle_sibling() may happily return a disallowed cpu in that case. > The mistake gets fixed in select_task_rq() which uses > select_fallback_rq() to find an allowed cpu instead. > > Could we fix the issue in find_energy_efficient_cpu() by a simple test > like below > > if (cpumask_test_cpu(prev_cpu, &p->cpus_allowed)) > prev_energy = best_energy = compute_energy(p, prev_cpu); > else > prev_energy = best_energy = ULONG_MAX; Right, that should work. I'll change this in v2. Thanks, Quentin
