Hi Peter, On 14/11/11 下午7:33, Peter Zijlstra wrote:
On Thu, Nov 06, 2014 at 10:40:49AM +0800, Wanpeng Li wrote:@@ -538,6 +539,46 @@ again: update_rq_clock(rq); dl_se->dl_throttled = 0; dl_se->dl_yielded = 0; + + /* + * So if we find that the rq the task was on is no longer + * available, we need to select a new rq. + */ + if (!rq->online) { + struct rq *later_rq = NULL; + + raw_spin_unlock(&rq->lock); + + later_rq = find_lock_later_rq(p, rq); + + if (!later_rq) { + int cpu; + + /* + * If cannot preempt any rq, fallback to pick any + * online cpu. + */ + for_each_cpu(cpu, &p->cpus_allowed) + if (cpu_online(cpu)) + later_rq = cpu_rq(cpu);cpu = cpumask_any_and(cpu_active_mask, tsk_cpus_allowed(p)); if (cpu >= nr_cpu_ids) /* fail */later_rq = cpu_rq(cpu);
Ok.
+ if (!later_rq) { + pr_warn("fail to find any online and task + will never come back to us\n"); + goto out; + } + } + + deactivate_task(rq, p, 0); + set_task_cpu(p, later_rq->cpu); + activate_task(later_rq, p, 0); + + resched_curr(later_rq); + + double_unlock_balance(rq, later_rq); + + goto out; + } + if (task_on_rq_queued(p)) { enqueue_task_dl(rq, p, ENQUEUE_REPLENISH); if (dl_task(rq->curr)) @@ -555,7 +596,7 @@ again: } unlock: raw_spin_unlock(&rq->lock); - +out: return HRTIMER_NORESTART; }@@ -1185,8 +1226,12 @@ static int find_later_rq(struct task_struct *task)* We have to consider system topology and task affinity * first, then we can look for a suitable cpu. */ - cpumask_copy(later_mask, task_rq(task)->rd->span); - cpumask_and(later_mask, later_mask, cpu_active_mask); + if (likely(task_rq(task)->online)) { + cpumask_copy(later_mask, task_rq(task)->rd->span); + cpumask_and(later_mask, later_mask, cpu_active_mask); + } else + /* for offline cpus we have a singleton rd */ + cpumask_copy(later_mask, cpu_active_mask); cpumask_and(later_mask, later_mask, &task->cpus_allowed); best_cpu = cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask);cpumask_copy(later_mask, cpu_active_mask); if (likely(task_rq(task)->online)) cpumask_and(later_mask, later_mask, task_rq(task)->rd->span); Is the same, right and less lines.
Thanks for your great help! I will fold these to my patch and send out a newer version tomorrow. ;-)
Regards, Wanpeng Li
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