aboutsummaryrefslogtreecommitdiffstats
path: root/fs/fs-writeback.c
diff options
context:
space:
mode:
authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2010-07-25 14:29:22 +0300
committerJens Axboe <jaxboe@fusionio.com>2010-08-07 18:53:56 +0200
commit6467716a37673e8d47b4984eb19839bdad0a8353 (patch)
tree8b2bfd38d53e31c47654162d4ce9220c4424a31d /fs/fs-writeback.c
parent253c34e9b10c30d3064be654b5b78fbc1a8b1896 (diff)
downloadmrst-s0i3-test-6467716a37673e8d47b4984eb19839bdad0a8353.tar.gz
mrst-s0i3-test-6467716a37673e8d47b4984eb19839bdad0a8353.tar.xz
mrst-s0i3-test-6467716a37673e8d47b4984eb19839bdad0a8353.zip
writeback: optimize periodic bdi thread wakeups
Whe the first inode for a bdi is marked dirty, we wake up the bdi thread which should take care of the periodic background write-out. However, the write-out will actually start only 'dirty_writeback_interval' centisecs later, so we can delay the wake-up. This change was requested by Nick Piggin who pointed out that if we delay the wake-up, we weed out 2 unnecessary contex switches, which matters because '__mark_inode_dirty()' is a hot-path function. This patch introduces a new function - 'bdi_wakeup_thread_delayed()', which sets up a timer to wake-up the bdi thread and returns. So the wake-up is delayed. We also delete the timer in bdi threads just before writing-back. And synchronously delete it when unregistering bdi. At the unregister point the bdi does not have any users, so no one can arm it again. Since now we take 'bdi->wb_lock' in the timer, which can execute in softirq context, we have to use 'spin_lock_bh()' for 'bdi->wb_lock'. This patch makes this change as well. This patch also moves the 'bdi_wb_init()' function down in the file to avoid forward-declaration of 'bdi_wakeup_thread_delayed()'. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c36
1 files changed, 11 insertions, 25 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 55f6e46e06f..bfa2df2c7ce 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -76,7 +76,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
{
trace_writeback_queue(bdi, work);
- spin_lock(&bdi->wb_lock);
+ spin_lock_bh(&bdi->wb_lock);
list_add_tail(&work->list, &bdi->work_list);
if (bdi->wb.task) {
wake_up_process(bdi->wb.task);
@@ -88,7 +88,7 @@ static void bdi_queue_work(struct backing_dev_info *bdi,
trace_writeback_nothread(bdi, work);
wake_up_process(default_backing_dev_info.wb.task);
}
- spin_unlock(&bdi->wb_lock);
+ spin_unlock_bh(&bdi->wb_lock);
}
static void
@@ -704,13 +704,13 @@ get_next_work_item(struct backing_dev_info *bdi)
{
struct wb_writeback_work *work = NULL;
- spin_lock(&bdi->wb_lock);
+ spin_lock_bh(&bdi->wb_lock);
if (!list_empty(&bdi->work_list)) {
work = list_entry(bdi->work_list.next,
struct wb_writeback_work, list);
list_del_init(&work->list);
}
- spin_unlock(&bdi->wb_lock);
+ spin_unlock_bh(&bdi->wb_lock);
return work;
}
@@ -810,6 +810,12 @@ int bdi_writeback_thread(void *data)
trace_writeback_thread_start(bdi);
while (!kthread_should_stop()) {
+ /*
+ * Remove own delayed wake-up timer, since we are already awake
+ * and we'll take care of the preriodic write-back.
+ */
+ del_timer(&wb->wakeup_timer);
+
pages_written = wb_do_writeback(wb, 0);
trace_writeback_pages_written(pages_written);
@@ -868,26 +874,6 @@ void wakeup_flusher_threads(long nr_pages)
rcu_read_unlock();
}
-/*
- * This function is used when the first inode for this bdi is marked dirty. It
- * wakes-up the corresponding bdi thread which should then take care of the
- * periodic background write-out of dirty inodes.
- */
-static void wakeup_bdi_thread(struct backing_dev_info *bdi)
-{
- spin_lock(&bdi->wb_lock);
- if (bdi->wb.task)
- wake_up_process(bdi->wb.task);
- else
- /*
- * When bdi tasks are inactive for long time, they are killed.
- * In this case we have to wake-up the forker thread which
- * should create and run the bdi thread.
- */
- wake_up_process(default_backing_dev_info.wb.task);
- spin_unlock(&bdi->wb_lock);
-}
-
static noinline void block_dump___mark_inode_dirty(struct inode *inode)
{
if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
@@ -1019,7 +1005,7 @@ out:
spin_unlock(&inode_lock);
if (wakeup_bdi)
- wakeup_bdi_thread(bdi);
+ bdi_wakeup_thread_delayed(bdi);
}
EXPORT_SYMBOL(__mark_inode_dirty);