linux-ext4 - [PATCH] ext4: yield during large unlinks

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Date:	Fri, 12 Jul 2013 17:45:14 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>
Subject: [PATCH] ext4: yield during large unlinks

During large unlink operations on files with extents, we can use a lot
of CPU time.  This adds a cond_resched() call when starting to examine
the next level of a multi-level extent tree.  Multi-level extent trees
are rare in the first place, and this should rarely be executed.

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
 fs/ext4/extents.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 3d99b18..cc4731fd 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2861,6 +2861,9 @@ again:
 				err = PTR_ERR(bh);
 				break;
 			}
+			/* Yield here to deal with large extent trees. Should be
+			 * a no-op if we did IO for the above sb_bread. */
+			cond_resched();
 			if (WARN_ON(i + 1 > depth)) {
 				err = -EIO;
 				break;
-- 
1.7.12.rc0.22.gcdd159b

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