Re: [PATCH v6 06/21] sched: Introduce task_cpu_possible_mask() to limit fallback rq selection
From: Peter Zijlstra <peterz@infradead.org>
Date: 2021-05-21 16:04:42
Also in:
linux-arm-kernel, lkml
On Tue, May 18, 2021 at 10:47:10AM +0100, Will Deacon wrote:
quoted hunk ↗ jump to hunk
diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h index 03dee12d2b61..bc4ac3c525e6 100644 --- a/include/linux/mmu_context.h +++ b/include/linux/mmu_context.h@@ -14,4 +14,12 @@ static inline void leave_mm(int cpu) { } #endif +/* + * CPUs that are capable of running task @p. By default, we assume a sane, + * homogeneous system. Must contain at least one active CPU. + */ +#ifndef task_cpu_possible_mask +# define task_cpu_possible_mask(p) cpu_possible_mask +#endif
#ifndef task_cpu_possible_mask # define task_cpu_possible_mask(p) cpu_possible_mask # define task_cpu_possible(cpu, p) true #else # define task_cpu_possible(cpu, p) cpumask_test_cpu((cpu), task_cpu_possible_mask(p)) #endif
quoted hunk ↗ jump to hunk
+ #endifdiff --git a/kernel/sched/core.c b/kernel/sched/core.c index 5226cc26a095..482f7fdca0e8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c@@ -1813,8 +1813,11 @@ static inline bool is_cpu_allowed(struct task_struct *p, int cpu) return cpu_online(cpu); /* Non kernel threads are not allowed during either online or offline. */ if (!(p->flags & PF_KTHREAD)) - return cpu_active(cpu);
+ return cpu_active(cpu) && task_cpu_possible(cpu, p);
/* KTHREAD_IS_PER_CPU is always allowed. */ if (kthread_is_per_cpu(p))
Would something like that make sense?