From: Jan Kara <jack@ucw.cz>
I found out that quota uses hash table with just 43 entries to hash dquot
entries. I guess that we can afford using one page for that
(quotactl(Q_GETQUOTA...), got faster like 3x for 4000 users). Attached patch
implements that.
---
25-akpm/fs/dquot.c | 47 +++++++++++++++++++++++++++++++-----------
25-akpm/include/linux/quota.h | 4 ---
2 files changed, 36 insertions(+), 15 deletions(-)
diff -puN fs/dquot.c~bigger-quota-hashtable fs/dquot.c
--- 25/fs/dquot.c~bigger-quota-hashtable Thu Apr 22 13:48:35 2004
+++ 25-akpm/fs/dquot.c Thu Apr 22 13:48:35 2004
@@ -194,7 +194,8 @@ static void put_quota_format(struct quot
static LIST_HEAD(inuse_list);
static LIST_HEAD(free_dquots);
-static struct list_head dquot_hash[NR_DQHASH];
+unsigned int dq_hash_bits, dq_hash_mask;
+static struct hlist_head *dquot_hash;
struct dqstats dqstats;
@@ -202,7 +203,8 @@ static void dqput(struct dquot *dquot);
static inline int const hashfn(struct super_block *sb, unsigned int id, int type)
{
- return((((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type)) % NR_DQHASH;
+ unsigned long tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type);
+ return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask;
}
/*
@@ -210,22 +212,22 @@ static inline int const hashfn(struct su
*/
static inline void insert_dquot_hash(struct dquot *dquot)
{
- struct list_head *head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id, dquot->dq_type);
- list_add(&dquot->dq_hash, head);
+ struct hlist_head *head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id, dquot->dq_type);
+ hlist_add_head(&dquot->dq_hash, head);
}
static inline void remove_dquot_hash(struct dquot *dquot)
{
- list_del_init(&dquot->dq_hash);
+ hlist_del_init(&dquot->dq_hash);
}
static inline struct dquot *find_dquot(unsigned int hashent, struct super_block *sb, unsigned int id, int type)
{
- struct list_head *head;
+ struct hlist_node *node;
struct dquot *dquot;
- for (head = dquot_hash[hashent].next; head != dquot_hash+hashent; head = head->next) {
- dquot = list_entry(head, struct dquot, dq_hash);
+ hlist_for_each (node, dquot_hash+hashent) {
+ dquot = hlist_entry(node, struct dquot, dq_hash);
if (dquot->dq_sb == sb && dquot->dq_id == id && dquot->dq_type == type)
return dquot;
}
@@ -541,7 +543,7 @@ static struct dquot *get_empty_dquot(str
sema_init(&dquot->dq_lock, 1);
INIT_LIST_HEAD(&dquot->dq_free);
INIT_LIST_HEAD(&dquot->dq_inuse);
- INIT_LIST_HEAD(&dquot->dq_hash);
+ INIT_HLIST_NODE(&dquot->dq_hash);
dquot->dq_sb = sb;
dquot->dq_type = type;
atomic_set(&dquot->dq_count, 1);
@@ -1695,18 +1697,39 @@ kmem_cache_t *dquot_cachep;
static int __init dquot_init(void)
{
int i;
+ unsigned long nr_hash, order;
- register_sysctl_table(sys_table, 0);
- for (i = 0; i < NR_DQHASH; i++)
- INIT_LIST_HEAD(dquot_hash + i);
printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
+ register_sysctl_table(sys_table, 0);
+
dquot_cachep = kmem_cache_create("dquot",
sizeof(struct dquot), sizeof(unsigned long) * 4,
SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT, NULL, NULL);
if (!dquot_cachep)
panic("Cannot create dquot SLAB cache");
+ order = 0;
+ dquot_hash = (struct hlist_head *)__get_free_pages(GFP_ATOMIC, order);
+ if (!dquot_hash)
+ panic("Cannot create dquot hash table");
+
+ /* Find power-of-two hlist_heads which can fit into allocation */
+ nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
+ dq_hash_bits = 0;
+ do {
+ dq_hash_bits++;
+ } while (nr_hash >> dq_hash_bits);
+ dq_hash_bits--;
+
+ nr_hash = 1UL << dq_hash_bits;
+ dq_hash_mask = nr_hash - 1;
+ for (i = 0; i < nr_hash; i++)
+ INIT_HLIST_HEAD(dquot_hash + i);
+
+ printk("Dquot-cache hash table entries: %ld (order %ld, %ld bytes)\n",
+ nr_hash, order, (PAGE_SIZE << order));
+
set_shrinker(DEFAULT_SEEKS, shrink_dqcache_memory);
return 0;
diff -puN include/linux/quota.h~bigger-quota-hashtable include/linux/quota.h
--- 25/include/linux/quota.h~bigger-quota-hashtable Thu Apr 22 13:48:35 2004
+++ 25-akpm/include/linux/quota.h Thu Apr 22 13:48:35 2004
@@ -201,8 +201,6 @@ struct dqstats {
extern struct dqstats dqstats;
-#define NR_DQHASH 43 /* Just an arbitrary number */
-
#define DQ_MOD_B 0 /* dquot modified since read */
#define DQ_BLKS_B 1 /* uid/gid has been warned about blk limit */
#define DQ_INODES_B 2 /* uid/gid has been warned about inode limit */
@@ -212,7 +210,7 @@ extern struct dqstats dqstats;
#define DQ_WAITFREE_B 6 /* dquot being waited (by invalidate_dquots) */
struct dquot {
- struct list_head dq_hash; /* Hash list in memory */
+ struct hlist_node dq_hash; /* Hash list in memory */
struct list_head dq_inuse; /* List of all quotas */
struct list_head dq_free; /* Free list element */
struct semaphore dq_lock; /* dquot IO lock */
_