Re: [PATCH] shrinks dentry struct

From: Paul Jackson (pj_at_sgi.com)
Date: 11/30/05

  • Next message: Paul Mackerras: "Re: Linux 2.6.15-rc3" 
    Date:	Tue, 29 Nov 2005 18:06:53 -0800
To: Eric Dumazet <dada1@cosmosbay.com>

    Eric,

    Would the following accomplish the same thing as your patch, to shrink
    UP dentry structs back to 128 bytes, with a smaller and less intrusive
    patch? 

    ---
 include/linux/dcache.h |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)
--- 2.6.15-rc2-mm1.orig/include/linux/dcache.h	2005-11-29 17:45:51.977352268 -0800
+++ 2.6.15-rc2-mm1/include/linux/dcache.h	2005-11-29 18:04:59.151307979 -0800
@@ -95,19 +95,24 @@ struct dentry {
 	struct qstr d_name;
 
 	struct list_head d_lru;		/* LRU list */
-	struct list_head d_child;	/* child of parent list */
+	union {				/* Fit 32 bit UP dentry in 128 bytes */
+		struct list_head du_child;	/* child of parent list */
+ 		struct rcu_head du_rcu;
+	} d_du;
 	struct list_head d_subdirs;	/* our children */
 	struct list_head d_alias;	/* inode alias list */
 	unsigned long d_time;		/* used by d_revalidate */
 	struct dentry_operations *d_op;
 	struct super_block *d_sb;	/* The root of the dentry tree */
 	void *d_fsdata;			/* fs-specific data */
- 	struct rcu_head d_rcu;
 	struct dcookie_struct *d_cookie; /* cookie, if any */
 	int d_mounted;
 	unsigned char d_iname[DNAME_INLINE_LEN_MIN];	/* small names */
 };
 
+#define d_child d_du.du_child
+#define d_rcu d_du.du_rcu
+
 struct dentry_operations {
 	int (*d_revalidate)(struct dentry *, struct nameidata *);
 	int (*d_hash) (struct dentry *, struct qstr *);
-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401
-
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