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sched/deadline: Reduce rq lock contention by eliminating locking of non-feasible target
This patch adds a check that prevents futile attempts to move DL tasks
to a CPU with active tasks of equal or earlier deadline. The same
behavior as commit 80e3d87b2c
("sched/rt: Reduce rq lock contention
by eliminating locking of non-feasible target") for rt class.
Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431496867-4194-3-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
a6c0e746fb
commit
9d51426242
1 changed files with 14 additions and 1 deletions
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@ -1012,7 +1012,9 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags)
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(p->nr_cpus_allowed > 1)) {
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int target = find_later_rq(p);
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if (target != -1)
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if (target != -1 &&
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dl_time_before(p->dl.deadline,
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cpu_rq(target)->dl.earliest_dl.curr))
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cpu = target;
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}
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rcu_read_unlock();
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@ -1359,6 +1361,17 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
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later_rq = cpu_rq(cpu);
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if (!dl_time_before(task->dl.deadline,
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later_rq->dl.earliest_dl.curr)) {
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/*
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* Target rq has tasks of equal or earlier deadline,
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* retrying does not release any lock and is unlikely
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* to yield a different result.
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*/
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later_rq = NULL;
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break;
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}
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/* Retry if something changed. */
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if (double_lock_balance(rq, later_rq)) {
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if (unlikely(task_rq(task) != rq ||
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