117 lines
3.6 KiB
Diff
117 lines
3.6 KiB
Diff
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From 8cbfcaa3935bfd3d5961719bd6598db2c8a3b7d3 Mon Sep 17 00:00:00 2001
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From: Luiz Capitulino <lcapitulino@redhat.com>
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Date: Fri, 27 May 2016 15:03:28 +0200
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Subject: [PATCH 102/365] mm: perform lru_add_drain_all() remotely
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lru_add_drain_all() works by scheduling lru_add_drain_cpu() to run
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on all CPUs that have non-empty LRU pagevecs and then waiting for
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the scheduled work to complete. However, workqueue threads may never
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have the chance to run on a CPU that's running a SCHED_FIFO task.
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This causes lru_add_drain_all() to block forever.
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This commit solves this problem by changing lru_add_drain_all()
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to drain the LRU pagevecs of remote CPUs. This is done by grabbing
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swapvec_lock and calling lru_add_drain_cpu().
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PS: This is based on an idea and initial implementation by
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Rik van Riel.
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Signed-off-by: Rik van Riel <riel@redhat.com>
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Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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mm/swap.c | 42 ++++++++++++++++++++++++++++++++----------
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1 file changed, 32 insertions(+), 10 deletions(-)
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diff --git a/mm/swap.c b/mm/swap.c
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index 796f3664e2fc..e360916a5c6d 100644
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--- a/mm/swap.c
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+++ b/mm/swap.c
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@@ -597,9 +597,15 @@ void lru_add_drain_cpu(int cpu)
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unsigned long flags;
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/* No harm done if a racing interrupt already did this */
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+#ifdef CONFIG_PREEMPT_RT_BASE
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+ local_lock_irqsave_on(rotate_lock, flags, cpu);
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+ pagevec_move_tail(pvec);
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+ local_unlock_irqrestore_on(rotate_lock, flags, cpu);
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+#else
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local_lock_irqsave(rotate_lock, flags);
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pagevec_move_tail(pvec);
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local_unlock_irqrestore(rotate_lock, flags);
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+#endif
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}
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pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
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@@ -667,12 +673,15 @@ void lru_add_drain(void)
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local_unlock_cpu(swapvec_lock);
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}
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-static void lru_add_drain_per_cpu(struct work_struct *dummy)
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+#ifdef CONFIG_PREEMPT_RT_BASE
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+static inline void remote_lru_add_drain(int cpu, struct cpumask *has_work)
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{
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- lru_add_drain();
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+ local_lock_on(swapvec_lock, cpu);
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+ lru_add_drain_cpu(cpu);
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+ local_unlock_on(swapvec_lock, cpu);
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}
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-static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
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+#else
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/*
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* lru_add_drain_wq is used to do lru_add_drain_all() from a WQ_MEM_RECLAIM
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@@ -692,6 +701,22 @@ static int __init lru_init(void)
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}
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early_initcall(lru_init);
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+static void lru_add_drain_per_cpu(struct work_struct *dummy)
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+{
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+ lru_add_drain();
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+}
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+
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+static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
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+static inline void remote_lru_add_drain(int cpu, struct cpumask *has_work)
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+{
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+ struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
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+
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+ INIT_WORK(work, lru_add_drain_per_cpu);
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+ queue_work_on(cpu, lru_add_drain_wq, work);
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+ cpumask_set_cpu(cpu, has_work);
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+}
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+#endif
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+
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void lru_add_drain_all(void)
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{
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static DEFINE_MUTEX(lock);
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@@ -703,21 +728,18 @@ void lru_add_drain_all(void)
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cpumask_clear(&has_work);
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for_each_online_cpu(cpu) {
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- struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
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-
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if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
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pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
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pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
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pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
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- need_activate_page_drain(cpu)) {
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- INIT_WORK(work, lru_add_drain_per_cpu);
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- queue_work_on(cpu, lru_add_drain_wq, work);
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- cpumask_set_cpu(cpu, &has_work);
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- }
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+ need_activate_page_drain(cpu))
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+ remote_lru_add_drain(cpu, &has_work);
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}
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+#ifndef CONFIG_PREEMPT_RT_BASE
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for_each_cpu(cpu, &has_work)
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flush_work(&per_cpu(lru_add_drain_work, cpu));
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+#endif
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put_online_cpus();
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mutex_unlock(&lock);
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--
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2.28.0
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