From: Ingo Molnar - minor can_migrate_task cleanup kernel/sched.c | 27 +++++++++++---------------- 1 files changed, 11 insertions(+), 16 deletions(-) diff -puN kernel/sched.c~sched-can-migrate-2.6.0-A2 kernel/sched.c --- 25/kernel/sched.c~sched-can-migrate-2.6.0-A2 2003-12-30 00:45:12.000000000 -0800 +++ 25-akpm/kernel/sched.c 2003-12-30 00:45:12.000000000 -0800 @@ -1146,25 +1146,25 @@ static inline void pull_task(runqueue_t } /* - * Previously: - * - * #define CAN_MIGRATE_TASK(p,rq,this_cpu) \ - * ((!idle || (NS_TO_JIFFIES(now - (p)->timestamp) > \ - * cache_decay_ticks)) && !task_running(rq, p) && \ - * cpu_isset(this_cpu, (p)->cpus_allowed)) + * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? */ - static inline int can_migrate_task(task_t *tsk, runqueue_t *rq, int this_cpu, int idle) { unsigned long delta = rq->timestamp_last_tick - tsk->timestamp; - if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks))) - return 0; + /* + * We do not migrate tasks that are: + * 1) running (obviously), or + * 2) cannot be migrated to this CPU due to cpus_allowed, or + * 3) are cache-hot on their current CPU. + */ if (task_running(rq, tsk)) return 0; if (!cpu_isset(this_cpu, tsk->cpus_allowed)) return 0; + if (!idle && (delta <= JIFFIES_TO_NS(cache_decay_ticks))) + return 0; return 1; } @@ -1226,13 +1226,6 @@ skip_bitmap: skip_queue: tmp = list_entry(curr, task_t, run_list); - /* - * We do not migrate tasks that are: - * 1) running (obviously), or - * 2) cannot be migrated to this CPU due to cpus_allowed, or - * 3) are cache-hot on their current CPU. - */ - curr = curr->prev; if (!can_migrate_task(tmp, busiest, this_cpu, idle)) { @@ -1242,6 +1235,8 @@ skip_queue: goto skip_bitmap; } pull_task(busiest, array, tmp, this_rq, this_cpu); + + /* Only migrate one task if we are idle */ if (!idle && --imbalance) { if (curr != head) goto skip_queue; _