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Message-Id: <1288704890-1858-1-git-send-email-tytso@mit.edu>
Date: Tue, 2 Nov 2010 09:34:50 -0400
From: Theodore Ts'o <tytso@....edu>
To: linux-ext4@...r.kernel.org
Cc: torvalds@...ux-foundation.org, Theodore Ts'o <tytso@....edu>
Subject: [PATCH] ext4: Remove useless spinlock in ext4_getattr()
Linus noted, and complained to me, that doing while lots of "git
diff"'s of kernel sources, these spinlocks were responsible for 27% of
the CPU on his two-processor system as reported by perf.
Git was doing lots of parallel stats, and this was putting a lot of
pressure on ext4_getattr(). A spinlock to protect a single
memory-to-memory copy is pointless, so remove it.
Signed-off-by: "Theodore Ts'o" <tytso@....edu>
---
fs/ext4/inode.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1916164..4d78342 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5410,9 +5410,7 @@ int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
* will return the blocks that include the delayed allocation
* blocks for this file.
*/
- spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks;
- spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9;
return 0;
--
1.7.3.1
--
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