]> git.openfabrics.org - ~shefty/rdma-dev.git/commitdiff
ext4: Remove useless spinlock in ext4_getattr()
authorTheodore Ts'o <tytso@mit.edu>
Tue, 2 Nov 2010 13:34:50 +0000 (09:34 -0400)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 2 Nov 2010 14:38:30 +0000 (10:38 -0400)
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
spinlock cost 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@mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/ext4/inode.c

index 1916164704667dc3c190ab327781933fa7c5f4b8..4d78342f3bf07ec61dbe8346eef88706aa5abebb 100644 (file)
@@ -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;