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authorLinus Torvalds <torvalds@linux-foundation.org>2011-08-06 22:45:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-08-06 22:53:23 -0700
commit3ddcd0569cd68f00f3beae9a7959b72918bb91f4 (patch)
tree3f7c591316560b1c22e2cc0700fbcd29aa3fbd7f /fs/inode.c
parent830c0f0edca67403d361fe976a25b17356c11f19 (diff)
downloadlinux-3ddcd0569cd68f00f3beae9a7959b72918bb91f4.tar.gz
vfs: optimize inode cache access patterns
The inode structure layout is largely random, and some of the vfs paths really do care. The path lookup in particular is already quite D$ intensive, and profiles show that accessing the 'inode->i_op->xyz' fields is quite costly. We already optimized the dcache to not unnecessarily load the d_op structure for members that are often NULL using the DCACHE_OP_xyz bits in dentry->d_flags, and this does something very similar for the inode ops that are used during pathname lookup. It also re-orders the fields so that the fields accessed by 'stat' are together at the beginning of the inode structure, and roughly in the order accessed. The effect of this seems to be in the 1-2% range for an empty kernel "make -j" run (which is fairly kernel-intensive, mostly in filename lookup), so it's visible. The numbers are fairly noisy, though, and likely depend a lot on exact microarchitecture. So there's more tuning to be done. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/inode.c')
-rw-r--r--fs/inode.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 5aab80dc008..73920d555c8 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -143,6 +143,7 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
inode->i_op = &empty_iops;
inode->i_fop = &empty_fops;
inode->i_nlink = 1;
+ inode->i_opflags = 0;
inode->i_uid = 0;
inode->i_gid = 0;
atomic_set(&inode->i_writecount, 0);