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Subject[patch 31/35] fs: icache per-zone inode LRU
Per-zone LRUs and shrinkers for inode cache.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

---
fs/inode.c | 84 ++++++++++++++++++++++++++++---------------------
include/linux/mmzone.h | 7 ++++
2 files changed, 56 insertions(+), 35 deletions(-)
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c 2010-10-19 14:38:31.000000000 +1100
+++ linux-2.6/fs/inode.c 2010-10-19 14:39:04.000000000 +1100
@@ -34,7 +34,7 @@
* s_inodes, i_sb_list
* inode_hash_bucket lock protects:
* inode hash table, i_hash
- * inode_lru_lock protects:
+ * zone->inode_lru_lock protects:
* inode_lru, i_lru
* wb->b_lock protects:
* b_io, b_more_io, b_dirty, i_io, i_lru
@@ -49,7 +49,7 @@
* Ordering:
* inode->i_lock
* inode_list_lglock
- * inode_lru_lock
+ * zone->inode_lru_lock
* wb->b_lock
* inode_hash_bucket lock
*/
@@ -100,8 +100,6 @@
* allowing for low-overhead inode sync() operations.
*/

-static LIST_HEAD(inode_lru);
-
struct inode_hash_bucket {
struct hlist_bl_head head;
};
@@ -127,8 +125,6 @@
DECLARE_LGLOCK(inode_list_lglock);
DEFINE_LGLOCK(inode_list_lglock);

-static DEFINE_SPINLOCK(inode_lru_lock);
-
/*
* iprune_sem provides exclusion between the kswapd or try_to_free_pages
* icache shrinking path, and the umount path. Without this exclusion,
@@ -166,7 +162,12 @@

int get_nr_inodes_unused(void)
{
- return inodes_stat.nr_unused;
+ int nr = 0;
+ struct zone *z;
+
+ for_each_populated_zone(z)
+ nr += z->inode_nr_lru;
+ return nr;
}

/*
@@ -177,6 +178,7 @@
{
#if defined(CONFIG_SYSCTL) && defined(CONFIG_PROC_FS)
inodes_stat.nr_inodes = get_nr_inodes();
+ inodes_stat.nr_unused = get_nr_inodes_unused();
return proc_dointvec(table, write, buffer, lenp, ppos);
#else
return -ENOSYS;
@@ -440,10 +442,12 @@
*/
void __inode_lru_list_add(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
- list_add(&inode->i_lru, &inode_lru);
- inodes_stat.nr_unused++;
- spin_unlock(&inode_lru_lock);
+ struct zone *z = page_zone(virt_to_page(inode));
+
+ spin_lock(&z->inode_lru_lock);
+ list_add(&inode->i_lru, &z->inode_lru);
+ z->inode_nr_lru++;
+ spin_unlock(&z->inode_lru_lock);
}

/*
@@ -451,10 +455,12 @@
*/
void __inode_lru_list_del(struct inode *inode)
{
- spin_lock(&inode_lru_lock);
+ struct zone *z = page_zone(virt_to_page(inode));
+
+ spin_lock(&z->inode_lru_lock);
list_del_init(&inode->i_lru);
- inodes_stat.nr_unused--;
- spin_unlock(&inode_lru_lock);
+ z->inode_nr_lru--;
+ spin_unlock(&z->inode_lru_lock);
}

/*
@@ -549,34 +555,35 @@
* If the inode has metadata buffers attached to mapping->private_list then
* try to remove them.
*/
-static void prune_icache(unsigned long nr_to_scan)
+static void prune_icache(struct zone *zone, unsigned long nr_to_scan)
{
LIST_HEAD(freeable);
unsigned long reap = 0;

down_read(&iprune_sem);
again:
- spin_lock(&inode_lru_lock);
+ spin_lock(&zone->inode_lru_lock);
for (; nr_to_scan; nr_to_scan--) {
struct inode *inode;

- if (list_empty(&inode_lru))
+ if (list_empty(&zone->inode_lru))
break;

- inode = list_entry(inode_lru.prev, struct inode, i_lru);
+ inode = list_entry(zone->inode_lru.prev, struct inode, i_lru);

if (!spin_trylock(&inode->i_lock)) {
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&zone->inode_lru_lock);
+ cpu_relax();
goto again;
}
if (inode->i_count || (inode->i_state & ~I_REFERENCED)) {
list_del_init(&inode->i_lru);
spin_unlock(&inode->i_lock);
- inodes_stat.nr_unused--;
+ zone->inode_nr_lru--;
continue;
}
if (inode->i_state & I_REFERENCED) {
- list_move(&inode->i_lru, &inode_lru);
+ list_move(&inode->i_lru, &zone->inode_lru);
inode->i_state &= ~I_REFERENCED;
spin_unlock(&inode->i_lock);
continue;
@@ -589,8 +596,8 @@
*
* We'll try to get it back if it becomes freeable.
*/
- list_move(&inode->i_lru, &inode_lru);
- spin_unlock(&inode_lru_lock);
+ list_move(&inode->i_lru, &zone->inode_lru);
+ spin_unlock(&zone->inode_lru_lock);
__iget(inode);
spin_unlock(&inode->i_lock);

@@ -598,8 +605,8 @@
reap += invalidate_mapping_pages(&inode->i_data,
0, -1);
iput(inode);
- spin_lock(&inode_lru_lock);
- if (inode == list_entry(inode_lru.next,
+ spin_lock(&zone->inode_lru_lock);
+ if (inode == list_entry(zone->inode_lru.next,
struct inode, i_lru)) {
if (spin_trylock(&inode->i_lock)) {
if (can_unuse(inode))
@@ -614,13 +621,13 @@
WARN_ON(inode->i_state & I_NEW);
inode->i_state |= I_FREEING;
spin_unlock(&inode->i_lock);
- inodes_stat.nr_unused--;
+ zone->inode_nr_lru--;
}
if (current_is_kswapd())
__count_vm_events(KSWAPD_INODESTEAL, reap);
else
__count_vm_events(PGINODESTEAL, reap);
- spin_unlock(&inode_lru_lock);
+ spin_unlock(&zone->inode_lru_lock);

dispose_list(&freeable);
up_read(&iprune_sem);
@@ -639,11 +646,10 @@
unsigned long total, unsigned long global,
unsigned long flags, gfp_t gfp_mask)
{
- static unsigned long nr_to_scan;
unsigned long nr;

- shrinker_add_scan(&nr_to_scan, scanned, global,
- inodes_stat.nr_unused,
+ shrinker_add_scan(&zone->inode_nr_scan, scanned, total,
+ zone->inode_nr_lru,
SHRINK_DEFAULT_SEEKS * 100 / sysctl_vfs_cache_pressure);
/*
* Nasty deadlock avoidance. We may hold various FS locks,
@@ -653,11 +659,12 @@
if (!(gfp_mask & __GFP_FS))
return;

- while ((nr = shrinker_do_scan(&nr_to_scan, SHRINK_BATCH))) {
- prune_icache(nr);
- count_vm_events(SLABS_SCANNED, nr);
- cond_resched();
- }
+ nr = ACCESS_ONCE(zone->inode_nr_scan);
+ if (nr < SHRINK_BATCH)
+ return;
+ zone->inode_nr_scan = 0;
+ prune_icache(zone, nr);
+ count_vm_events(SLABS_SCANNED, nr);
}

static struct shrinker icache_shrinker = {
@@ -1830,6 +1837,7 @@
void __init inode_init(void)
{
int loop;
+ struct zone *zone;

/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache",
@@ -1838,6 +1846,12 @@
(SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
SLAB_MEM_SPREAD),
init_once);
+ for_each_zone(zone) {
+ spin_lock_init(&zone->inode_lru_lock);
+ INIT_LIST_HEAD(&zone->inode_lru);
+ zone->inode_nr_lru = 0;
+ zone->inode_nr_scan = 0;
+ }
register_shrinker(&icache_shrinker);

lg_lock_init(inode_list_lglock);
Index: linux-2.6/include/linux/mmzone.h
===================================================================
--- linux-2.6.orig/include/linux/mmzone.h 2010-10-19 14:19:19.000000000 +1100
+++ linux-2.6/include/linux/mmzone.h 2010-10-19 14:38:33.000000000 +1100
@@ -362,6 +362,13 @@


ZONE_PADDING(_pad2_)
+
+ spinlock_t inode_lru_lock;
+ struct list_head inode_lru;
+ unsigned long inode_nr_lru;
+ unsigned long inode_nr_scan;
+
+ ZONE_PADDING(_pad3_)
/* Rarely used or read-mostly fields */

/*



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