From 5160ee6fc891a9ca114be0e90fa6655647bb64b2 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 8 Jan 2006 01:03:32 -0800 Subject: [PATCH] shrink dentry struct Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet Cc: Dipankar Sarma Cc: Maneesh Soni Cc: Miklos Szeredi Cc: "Paul E. McKenney" Cc: Ian Kent Cc: Paul Jackson Cc: Al Viro Cc: Christoph Hellwig Cc: Trond Myklebust Cc: Neil Brown Cc: James Morris Cc: Stephen Smalley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/usb/core/inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/usb/core/inode.c') diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c index c44bbedec817..4ddc453023a2 100644 --- a/drivers/usb/core/inode.c +++ b/drivers/usb/core/inode.c @@ -186,7 +186,7 @@ static void update_bus(struct dentry *bus) down(&bus->d_inode->i_sem); - list_for_each_entry(dev, &bus->d_subdirs, d_child) + list_for_each_entry(dev, &bus->d_subdirs, d_u.d_child) if (dev->d_inode) update_dev(dev); @@ -203,7 +203,7 @@ static void update_sb(struct super_block *sb) down(&root->d_inode->i_sem); - list_for_each_entry(bus, &root->d_subdirs, d_child) { + list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) { if (bus->d_inode) { switch (S_IFMT & bus->d_inode->i_mode) { case S_IFDIR: @@ -319,7 +319,7 @@ static int usbfs_empty (struct dentry *dentry) spin_lock(&dcache_lock); list_for_each(list, &dentry->d_subdirs) { - struct dentry *de = list_entry(list, struct dentry, d_child); + struct dentry *de = list_entry(list, struct dentry, d_u.d_child); if (usbfs_positive(de)) { spin_unlock(&dcache_lock); return 0; -- cgit From 1b1dcc1b57a49136f118a0f16367256ff9994a69 Mon Sep 17 00:00:00 2001 From: Jes Sorensen Date: Mon, 9 Jan 2006 15:59:24 -0800 Subject: [PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_sem This patch converts the inode semaphore to a mutex. I have tested it on XFS and compiled as much as one can consider on an ia64. Anyway your luck with it might be different. Modified-by: Ingo Molnar (finished the conversion) Signed-off-by: Jes Sorensen Signed-off-by: Ingo Molnar --- drivers/usb/core/inode.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) (limited to 'drivers/usb/core/inode.c') diff --git a/drivers/usb/core/inode.c b/drivers/usb/core/inode.c index 4ddc453023a2..3cf945cc5b9a 100644 --- a/drivers/usb/core/inode.c +++ b/drivers/usb/core/inode.c @@ -184,13 +184,13 @@ static void update_bus(struct dentry *bus) bus->d_inode->i_gid = busgid; bus->d_inode->i_mode = S_IFDIR | busmode; - down(&bus->d_inode->i_sem); + mutex_lock(&bus->d_inode->i_mutex); list_for_each_entry(dev, &bus->d_subdirs, d_u.d_child) if (dev->d_inode) update_dev(dev); - up(&bus->d_inode->i_sem); + mutex_unlock(&bus->d_inode->i_mutex); } static void update_sb(struct super_block *sb) @@ -201,7 +201,7 @@ static void update_sb(struct super_block *sb) if (!root) return; - down(&root->d_inode->i_sem); + mutex_lock(&root->d_inode->i_mutex); list_for_each_entry(bus, &root->d_subdirs, d_u.d_child) { if (bus->d_inode) { @@ -219,7 +219,7 @@ static void update_sb(struct super_block *sb) } } - up(&root->d_inode->i_sem); + mutex_unlock(&root->d_inode->i_mutex); } static int remount(struct super_block *sb, int *flags, char *data) @@ -333,10 +333,10 @@ static int usbfs_empty (struct dentry *dentry) static int usbfs_unlink (struct inode *dir, struct dentry *dentry) { struct inode *inode = dentry->d_inode; - down(&inode->i_sem); + mutex_lock(&inode->i_mutex); dentry->d_inode->i_nlink--; dput(dentry); - up(&inode->i_sem); + mutex_unlock(&inode->i_mutex); d_delete(dentry); return 0; } @@ -346,7 +346,7 @@ static int usbfs_rmdir(struct inode *dir, struct dentry *dentry) int error = -ENOTEMPTY; struct inode * inode = dentry->d_inode; - down(&inode->i_sem); + mutex_lock(&inode->i_mutex); dentry_unhash(dentry); if (usbfs_empty(dentry)) { dentry->d_inode->i_nlink -= 2; @@ -355,7 +355,7 @@ static int usbfs_rmdir(struct inode *dir, struct dentry *dentry) dir->i_nlink--; error = 0; } - up(&inode->i_sem); + mutex_unlock(&inode->i_mutex); if (!error) d_delete(dentry); dput(dentry); @@ -380,7 +380,7 @@ static loff_t default_file_lseek (struct file *file, loff_t offset, int orig) { loff_t retval = -EINVAL; - down(&file->f_dentry->d_inode->i_sem); + mutex_lock(&file->f_dentry->d_inode->i_mutex); switch(orig) { case 0: if (offset > 0) { @@ -397,7 +397,7 @@ static loff_t default_file_lseek (struct file *file, loff_t offset, int orig) default: break; } - up(&file->f_dentry->d_inode->i_sem); + mutex_unlock(&file->f_dentry->d_inode->i_mutex); return retval; } @@ -480,7 +480,7 @@ static int fs_create_by_name (const char *name, mode_t mode, } *dentry = NULL; - down(&parent->d_inode->i_sem); + mutex_lock(&parent->d_inode->i_mutex); *dentry = lookup_one_len(name, parent, strlen(name)); if (!IS_ERR(dentry)) { if ((mode & S_IFMT) == S_IFDIR) @@ -489,7 +489,7 @@ static int fs_create_by_name (const char *name, mode_t mode, error = usbfs_create (parent->d_inode, *dentry, mode); } else error = PTR_ERR(dentry); - up(&parent->d_inode->i_sem); + mutex_unlock(&parent->d_inode->i_mutex); return error; } @@ -528,7 +528,7 @@ static void fs_remove_file (struct dentry *dentry) if (!parent || !parent->d_inode) return; - down(&parent->d_inode->i_sem); + mutex_lock(&parent->d_inode->i_mutex); if (usbfs_positive(dentry)) { if (dentry->d_inode) { if (S_ISDIR(dentry->d_inode->i_mode)) @@ -538,7 +538,7 @@ static void fs_remove_file (struct dentry *dentry) dput(dentry); } } - up(&parent->d_inode->i_sem); + mutex_unlock(&parent->d_inode->i_mutex); } /* --------------------------------------------------------------------- */ -- cgit