From 71927e84e0aebfbe5a91565c3b207af25a4e9162 Mon Sep 17 00:00:00 2001
From: Wu Fengguang <fengguang.wu@intel.com>
Date: Thu, 13 Jan 2011 15:45:46 -0800
Subject: writeback: trace wakeup event for background writeback

This tracks when balance_dirty_pages() tries to wakeup the flusher thread
for background writeback (if it was not started already).

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Engelhardt <jengelh@medozas.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/fs-writeback.c | 1 +
 1 file changed, 1 insertion(+)

(limited to 'fs/fs-writeback.c')

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 3a07f6d..482de0a 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -169,6 +169,7 @@ void bdi_start_background_writeback(struct backing_dev_info *bdi)
 	 * We just wake up the flusher thread. It will perform background
 	 * writeback as soon as there is no other work to do.
 	 */
+	trace_writeback_wake_background(bdi);
 	spin_lock_bh(&bdi->wb_lock);
 	bdi_wakeup_flusher(bdi);
 	spin_unlock_bh(&bdi->wb_lock);
-- 
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