From: Xunlei Pang <pang.xunlei@linaro.org>
To: linux-kernel@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@gmail.com>,
Xunlei Pang <pang.xunlei@linaro.org>
Subject: [PATCH 2/5] sched/deadline: Remove cpu_active_mask from cpudl_find()
Date: Mon, 19 Jan 2015 04:49:37 +0000 [thread overview]
Message-ID: <1421642980-10045-2-git-send-email-pang.xunlei@linaro.org> (raw)
In-Reply-To: <1421642980-10045-1-git-send-email-pang.xunlei@linaro.org>
cpu_active_mask is rarely changeable, 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(causing a task put onto a dying cpu) which
rq_offline_dl() can't handle timely, then it can be handled
through _cpu_down()->...->multi_cpu_stop()->migration_call()
->migrate_tasks(), preventing the task from hanging on the
dead cpu.
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org>
---
kernel/sched/cpudeadline.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index fd9d3fb..c6acb07 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -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) &&
--
1.9.1
next prev parent reply other threads:[~2015-01-19 4:51 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-19 4:49 [PATCH 1/5] sched/deadline: Modify cpudl::free_cpus to reflect rd->online Xunlei Pang
2015-01-19 4:49 ` Xunlei Pang [this message]
2015-01-27 15:04 ` [PATCH 2/5] sched/deadline: Remove cpu_active_mask from cpudl_find() Peter Zijlstra
2015-02-04 14:36 ` [tip:sched/core] " tip-bot for Xunlei Pang
2015-01-19 4:49 ` [PATCH 3/5] sched/deadline: Fix wrong cpudl_find() in check_preempt_equal_dl() Xunlei Pang
2015-01-27 12:48 ` Peter Zijlstra
2015-01-27 14:15 ` Peter Zijlstra
2015-01-27 16:47 ` Peter Zijlstra
2015-01-28 15:18 ` Xunlei Pang
2015-01-19 4:49 ` [PATCH 4/5] sched/rt: Consider deadline tasks in cpupri_find() Xunlei Pang
2015-01-27 12:58 ` Peter Zijlstra
2015-01-27 14:18 ` Peter Zijlstra
2015-01-27 23:04 ` Steven Rostedt
2015-01-28 15:21 ` Xunlei Pang
2015-01-19 4:49 ` [PATCH 5/5] sched/rt: Optimize find_lowest_rq() to select a cache hot cpu Xunlei Pang
2015-01-27 14:21 ` Peter Zijlstra
2015-01-27 14:56 ` Steven Rostedt
2015-01-27 16:28 ` Peter Zijlstra
2015-01-29 16:42 ` Xunlei Pang
2015-01-29 17:17 ` Steven Rostedt
2015-01-29 19:23 ` Peter Zijlstra
2015-02-04 13:07 ` Xunlei Pang
2015-01-23 18:09 ` [PATCH 1/5] sched/deadline: Modify cpudl::free_cpus to reflect rd->online Xunlei Pang
2015-02-01 17:53 ` [tip:sched/core] sched/deadline: Modify cpudl:: free_cpus " tip-bot for Xunlei Pang
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