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sched/deadline: Remove cpu_active_mask from cpudl_find()

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cpu_active_mask is rarely changed (only on hotplug), so remove this
operation to gain a little performance.

If there is a change in cpu_active_mask, rq_online_dl() and
rq_offline_dl() should take care of it normally, so cpudl::free_cpus
carries enough information for us.

For the rare case when a task is put onto a dying cpu (which
rq_offline_dl() can't handle in a timely fashion), it will be
handled through _cpu_down()->...->multi_cpu_stop()->migration_call()
->migrate_tasks(), preventing the task from hanging on the
dead cpu.

Cc: Juri Lelli <[email protected]>
Signed-off-by: Xunlei Pang <[email protected]>
[peterz: changelog]
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Cc: Linus Torvalds <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>
This commit is contained in:
Xunlei Pang authored and Ingo Molnar committed 2015-02-04 07:52:29 +01:00
1 parent 868933359a
commit 9659e1eeee
1 file changed
+1 -2
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kernel/sched/cpudeadline.c
+1 -2
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@@ -108,8 +108,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
const struct sched_dl_entity *dl_se = &p->dl;
if (later_mask &&
cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed) &&
cpumask_and(later_mask, later_mask, cpu_active_mask)) {
cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
best_cpu = cpumask_any(later_mask);
goto out;
} else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&