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Subject[PATCH] fs: super: do not cacheline align s_{inode,dentry}_lru
Date
super_block->s_{inode,dentry}_lru were made cacheline aligned, because
the list_lru struct had a spinlock and a list embedded to it and
therefore could be actively modified.

Today, struct list_lru is, in fact, read-only: the lists and locks live
in list_lru_node's, which list_lru points to. The list_lru_node struct
is already cacheline aligned by definition.

So let us drop the cacheline aligned annotation in order not to waste
space in struct super_block.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
---
include/linux/fs.h | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0bd9669ce91d..790e534adbc7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1309,12 +1309,9 @@ struct super_block {
struct workqueue_struct *s_dio_done_wq;
struct hlist_head s_pins;

- /*
- * Keep the lru lists last in the structure so they always sit on their
- * own individual cachelines.
- */
- struct list_lru s_dentry_lru ____cacheline_aligned_in_smp;
- struct list_lru s_inode_lru ____cacheline_aligned_in_smp;
+ struct list_lru s_dentry_lru;
+ struct list_lru s_inode_lru;
+
struct rcu_head rcu;

/*
--
1.7.10.4


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