[patch 41/52] fs: icache reduce atomics

npiggin
2010-06-24T03:16:48Z

[-- Attachment #1: fs-inode-nr_inodes.patch --]
[-- Type: text/plain, Size: 6611 bytes --]

Put inode counters under locks to reduce atomics.

Signed-off-by: Nick Piggin <npiggin@suse.de>
---
fs/fs-writeback.c | 6 ++----
fs/inode.c | 30 ++++++++++++------------------
include/linux/fs.h | 4 ++--
3 files changed, 16 insertions(+), 24 deletions(-)

Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -141,8 +141,8 @@ static DECLARE_RWSEM(iprune_sem);
* Statistics gathering..
*/
struct inodes_stat_t inodes_stat = {
- .nr_inodes = ATOMIC_INIT(0),
- .nr_unused = ATOMIC_INIT(0),
+ .nr_inodes = 0,
+ .nr_unused = 0,
};

static struct kmem_cache *inode_cachep __read_mostly;
@@ -390,7 +390,6 @@ static void dispose_list(struct list_hea
destroy_inode(inode);
nr_disposed++;
}
- atomic_sub(nr_disposed, &inodes_stat.nr_inodes);
}

/*
@@ -399,7 +398,7 @@ static void dispose_list(struct list_hea
static int invalidate_list(struct list_head *head, struct list_head *dispose)
{
struct list_head *next;
- int busy = 0, count = 0;
+ int busy = 0;

next = head->next;
for (;;) {
@@ -419,19 +418,17 @@ static int invalidate_list(struct list_h
if (!inode->i_count) {
spin_lock(&wb_inode_list_lock);
list_del(&inode->i_list);
+ inodes_stat.nr_unused--;
spin_unlock(&wb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
list_add(&inode->i_list, dispose);
- count++;
continue;
}
spin_unlock(&inode->i_lock);
busy = 1;
}
- /* only unused inodes may be cached with i_count zero */
- atomic_sub(count, &inodes_stat.nr_unused);
return busy;
}

@@ -483,7 +480,6 @@ EXPORT_SYMBOL(invalidate_inodes);
static void prune_icache(int nr_to_scan)
{
LIST_HEAD(freeable);
- int nr_pruned = 0;
unsigned long reap = 0;

down_read(&iprune_sem);
@@ -504,7 +500,7 @@ again:
if (inode->i_count || (inode->i_state & ~I_REFERENCED)) {
list_del_init(&inode->i_list);
spin_unlock(&inode->i_lock);
- atomic_dec(&inodes_stat.nr_unused);
+ inodes_stat.nr_unused--;
continue;
}
if (inode->i_state) {
@@ -530,9 +526,8 @@ again:
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- nr_pruned++;
+ inodes_stat.nr_unused--;
}
- atomic_sub(nr_pruned, &inodes_stat.nr_unused);
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
@@ -564,8 +559,7 @@ static int shrink_icache_memory(int nr,
return -1;
prune_icache(nr);
}
- return (atomic_read(&inodes_stat.nr_unused) / 100) *
- sysctl_vfs_cache_pressure;
+ return inodes_stat.nr_unused / 100 * sysctl_vfs_cache_pressure;
}

static struct shrinker icache_shrinker = {
@@ -661,9 +655,9 @@ static inline void
__inode_add_to_lists(struct super_block *sb, struct inode_hash_bucket *b,
struct inode *inode)
{
- atomic_inc(&inodes_stat.nr_inodes);
spin_lock(&sb_inode_list_lock);
list_add_rcu(&inode->i_sb_list, &sb->s_inodes);
+ inodes_stat.nr_inodes++;
spin_unlock(&sb_inode_list_lock);
if (b) {
spin_lock_bucket(b);
@@ -1309,17 +1303,17 @@ void generic_delete_inode(struct inode *
if (!list_empty(&inode->i_list)) {
spin_lock(&wb_inode_list_lock);
list_del_init(&inode->i_list);
- spin_unlock(&wb_inode_list_lock);
if (!inode->i_state)
- atomic_dec(&inodes_stat.nr_unused);
+ inodes_stat.nr_unused--;
+ spin_unlock(&wb_inode_list_lock);
}
spin_lock(&sb_inode_list_lock);
list_del_rcu(&inode->i_sb_list);
+ inodes_stat.nr_inodes--;
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- atomic_dec(&inodes_stat.nr_inodes);

if (op->delete_inode) {
void (*delete)(struct inode *) = op->delete_inode;
@@ -1367,8 +1361,8 @@ int generic_detach_inode(struct inode *i
list_empty(&inode->i_list)) {
spin_lock(&wb_inode_list_lock);
list_add(&inode->i_list, &inode_unused);
+ inodes_stat.nr_unused++;
spin_unlock(&wb_inode_list_lock);
- atomic_inc(&inodes_stat.nr_unused);
}
spin_unlock(&inode->i_lock);
return 0;
@@ -1385,17 +1379,17 @@ int generic_detach_inode(struct inode *i
if (!list_empty(&inode->i_list)) {
spin_lock(&wb_inode_list_lock);
list_del_init(&inode->i_list);
- spin_unlock(&wb_inode_list_lock);
if (!inode->i_state)
- atomic_dec(&inodes_stat.nr_unused);
+ inodes_stat.nr_unused--;
+ spin_unlock(&wb_inode_list_lock);
}
spin_lock(&sb_inode_list_lock);
list_del_rcu(&inode->i_sb_list);
+ inodes_stat.nr_inodes--;
spin_unlock(&sb_inode_list_lock);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- atomic_dec(&inodes_stat.nr_inodes);
return 1;
}
EXPORT_SYMBOL_GPL(generic_detach_inode);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -31,6 +31,12 @@
#define SEEK_END 2 /* seek relative to end of file */
#define SEEK_MAX SEEK_END

+struct inodes_stat_t {
+ int nr_inodes;
+ int nr_unused;
+ int dummy[5]; /* padding for sysctl ABI compatibility */
+};
+
/* And dynamically-tunable limits and defaults: */
struct files_stat_struct {
int nr_files; /* read only */
@@ -411,12 +417,6 @@ typedef int (get_block_t)(struct inode *
typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
ssize_t bytes, void *private);

-struct inodes_stat_t {
- atomic_t nr_inodes;
- atomic_t nr_unused;
- int dummy[5]; /* padding for sysctl ABI compatibility */
-};
-
/*
* Attribute flags. These should be or-ed together to figure out what
* has been changed!
Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -904,8 +904,7 @@ static long wb_check_old_data_flush(stru
wb->last_old_flush = jiffies;
nr_pages = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS) +
- (atomic_read(&inodes_stat.nr_inodes) -
- atomic_read(&inodes_stat.nr_unused));
+ inodes_stat.nr_inodes - inodes_stat.nr_unused;

if (nr_pages) {
struct wb_writeback_args args = {
@@ -1258,8 +1257,7 @@ void writeback_inodes_sb(struct super_bl
long nr_to_write;

nr_to_write = nr_dirty + nr_unstable +
- (atomic_read(&inodes_stat.nr_inodes) -
- atomic_read(&inodes_stat.nr_unused));
+ inodes_stat.nr_inodes - inodes_stat.nr_unused;

bdi_start_writeback(sb->s_bdi, sb, nr_to_write);
}