[patch 43/52] fs: icache per-cpu nr_inodes counter

npiggin
2010-06-24T03:25:44Z

[-- Attachment #1: fs-nr_inodes-percpu.patch --]
[-- Type: text/plain, Size: 4900 bytes --]

From: Eric Dumazet <dada1@cosmosbay.com>

Avoids cache line ping pongs between cpus and prepare next patch,
because updates of nr_inodes dont need inode_lock anymore.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
---
fs/fs-writeback.c | 4 ++--
fs/inode.c | 31 ++++++++++++++++++++++++++++---
include/linux/fs.h | 5 ++++-
kernel/sysctl.c | 4 ++--
4 files changed, 36 insertions(+), 8 deletions(-)

Index: linux-2.6/fs/fs-writeback.c
===================================================================
--- linux-2.6.orig/fs/fs-writeback.c
+++ linux-2.6/fs/fs-writeback.c
@@ -904,7 +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) +
- inodes_stat.nr_inodes - inodes_stat.nr_unused;
+ get_nr_inodes() - inodes_stat.nr_unused;

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

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

bdi_start_writeback(sb->s_bdi, sb, nr_to_write);
}
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -144,9 +144,33 @@ struct inodes_stat_t inodes_stat = {
.nr_inodes = 0,
.nr_unused = 0,
};
+struct percpu_counter nr_inodes;

static struct kmem_cache *inode_cachep __read_mostly;

+int get_nr_inodes(void)
+{
+ return percpu_counter_sum_positive(&nr_inodes);
+}
+
+/*
+ * Handle nr_dentry sysctl
+ */
+#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
+int proc_nr_inodes(ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ inodes_stat.nr_inodes = get_nr_inodes();
+ return proc_dointvec(table, write, buffer, lenp, ppos);
+}
+#else
+int proc_nr_inodes(ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ return -ENOSYS;
+}
+#endif
+
static void wake_up_inode(struct inode *inode)
{
/*
@@ -657,8 +681,8 @@ __inode_add_to_lists(struct super_block
{
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);
+ percpu_counter_inc(&nr_inodes);
if (b) {
spin_lock_bucket(b);
hlist_bl_add_head_rcu(&inode->i_hash, &b->head);
@@ -1337,8 +1361,8 @@ void generic_delete_inode(struct inode *
}
spin_lock(&sb_inode_list_lock);
list_del_rcu(&inode->i_sb_list);
- inodes_stat.nr_inodes--;
spin_unlock(&sb_inode_list_lock);
+ percpu_counter_dec(&nr_inodes);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
@@ -1413,8 +1437,8 @@ int generic_detach_inode(struct inode *i
}
spin_lock(&sb_inode_list_lock);
list_del_rcu(&inode->i_sb_list);
- inodes_stat.nr_inodes--;
spin_unlock(&sb_inode_list_lock);
+ percpu_counter_dec(&nr_inodes);
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
@@ -1723,6 +1747,7 @@ void __init inode_init(void)
{
int loop;

+ percpu_counter_init(&nr_inodes, 0);
/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache",
sizeof(struct inode),
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -406,6 +406,8 @@ extern struct files_stat_struct files_st
extern int get_max_files(void);
extern int sysctl_nr_open;
extern struct inodes_stat_t inodes_stat;
+extern struct percpu_counter nr_inodes;
+extern int get_nr_inodes(void);
extern int leases_enable, lease_break_time;
#ifdef CONFIG_DNOTIFY
extern int dir_notify_enable;
@@ -2514,7 +2516,8 @@ ssize_t simple_attr_write(struct file *f
struct ctl_table;
int proc_nr_files(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
-
+int proc_nr_inodes(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
int __init get_filesystem_list(char *buf);

#define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
Index: linux-2.6/kernel/sysctl.c
===================================================================
--- linux-2.6.orig/kernel/sysctl.c
+++ linux-2.6/kernel/sysctl.c
@@ -1338,14 +1338,14 @@ static struct ctl_table fs_table[] = {
.data = &inodes_stat,
.maxlen = 2*sizeof(int),
.mode = 0444,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_nr_inodes,
},
{
.procname = "inode-state",
.data = &inodes_stat,
.maxlen = 7*sizeof(int),
.mode = 0444,
- .proc_handler = proc_dointvec,
+ .proc_handler = proc_nr_inodes,
},
{
.procname = "file-nr",