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authorTim Chen <tim.c.chen@linux.intel.com>2017-08-25 09:13:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-14 09:56:18 -0700
commit11a19c7b099f96d00a8dec52bfbb8475e89b6745 (patch)
treef1b357ea18df807c38355591ff929aaf4bb3e3f0
parent2554db916586b228ce93e6f74a12fd7fe430a004 (diff)
sched/wait: Introduce wakeup boomark in wake_up_page_bit
Now that we have added breaks in the wait queue scan and allow bookmark on scan position, we put this logic in the wake_up_page_bit function. We can have very long page wait list in large system where multiple pages share the same wait list. We break the wake up walk here to allow other cpus a chance to access the list, and not to disable the interrupts when traversing the list for too long. This reduces the interrupt and rescheduling latency, and excessive page wait queue lock hold time. [ v2: Remove bookmark_wake_function ] Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/wait.h2
-rw-r--r--kernel/sched/wait.c7
-rw-r--r--mm/filemap.c22
3 files changed, 30 insertions, 1 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 78401ef02d29..87c4641023fb 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -185,6 +185,8 @@ __remove_wait_queue(struct wait_queue_head *wq_head, struct wait_queue_entry *wq
void __wake_up(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, void *key);
+void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
+ unsigned int mode, void *key, wait_queue_entry_t *bookmark);
void __wake_up_sync_key(struct wait_queue_head *wq_head, unsigned int mode, int nr, void *key);
void __wake_up_locked(struct wait_queue_head *wq_head, unsigned int mode, int nr);
void __wake_up_sync(struct wait_queue_head *wq_head, unsigned int mode, int nr);
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 70701ef50465..98feab7933c7 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -165,6 +165,13 @@ void __wake_up_locked_key(struct wait_queue_head *wq_head, unsigned int mode, vo
}
EXPORT_SYMBOL_GPL(__wake_up_locked_key);
+void __wake_up_locked_key_bookmark(struct wait_queue_head *wq_head,
+ unsigned int mode, void *key, wait_queue_entry_t *bookmark)
+{
+ __wake_up_common(wq_head, mode, 1, 0, key, bookmark);
+}
+EXPORT_SYMBOL_GPL(__wake_up_locked_key_bookmark);
+
/**
* __wake_up_sync_key - wake up threads blocked on a waitqueue.
* @wq_head: the waitqueue
diff --git a/mm/filemap.c b/mm/filemap.c
index 9d21afd692b9..8c88e186a773 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -909,13 +909,33 @@ static void wake_up_page_bit(struct page *page, int bit_nr)
wait_queue_head_t *q = page_waitqueue(page);
struct wait_page_key key;
unsigned long flags;
+ wait_queue_entry_t bookmark;
key.page = page;
key.bit_nr = bit_nr;
key.page_match = 0;
+ bookmark.flags = 0;
+ bookmark.private = NULL;
+ bookmark.func = NULL;
+ INIT_LIST_HEAD(&bookmark.entry);
+
spin_lock_irqsave(&q->lock, flags);
- __wake_up_locked_key(q, TASK_NORMAL, &key);
+ __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+
+ while (bookmark.flags & WQ_FLAG_BOOKMARK) {
+ /*
+ * Take a breather from holding the lock,
+ * allow pages that finish wake up asynchronously
+ * to acquire the lock and remove themselves
+ * from wait queue
+ */
+ spin_unlock_irqrestore(&q->lock, flags);
+ cpu_relax();
+ spin_lock_irqsave(&q->lock, flags);
+ __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
+ }
+
/*
* It is possible for other pages to have collided on the waitqueue
* hash, so in that case check for a page match. That prevents a long-