[4/4] eliminate inode waitqueue hashtable

William Lee Irwin III
2004-08-28T09:27:17Z

On Sat, Aug 28, 2004 at 02:23:37AM -0700, William Lee Irwin III wrote:
> Eliminate the bh waitqueue hashtable using bit_waitqueue() via
> wait_on_bit() and wake_up_bit() to locate the waitqueue head associated
> with a bit.

Eliminate the inode waitqueue hashtable using bit_waitqueue() via
wait_on_bit() and wake_up_bit() to locate the waitqueue head associated
with a bit.

Index: mm1-2.6.9-rc1/fs/inode.c
===================================================================
--- mm1-2.6.9-rc1.orig/fs/inode.c 2004-08-26 15:04:02.000000000 -0700
+++ mm1-2.6.9-rc1/fs/inode.c 2004-08-27 22:15:43.602377440 -0700
@@ -1257,37 +1257,17 @@

#endif

-/*
- * Hashed waitqueues for wait_on_inode(). The table is pretty small - the
- * kernel doesn't lock many inodes at the same time.
- */
-#define I_WAIT_TABLE_ORDER 3
-static struct i_wait_queue_head {
- wait_queue_head_t wqh;
-} ____cacheline_aligned_in_smp i_wait_queue_heads[1<<I_WAIT_TABLE_ORDER];
+#define __I_LOCK 3

-/*
- * Return the address of the waitqueue_head to be used for this inode
- */
-static wait_queue_head_t *i_waitq_head(struct inode *inode)
+static int inode_wait(void *word)
{
- return &i_wait_queue_heads[hash_ptr(inode, I_WAIT_TABLE_ORDER)].wqh;
+ schedule();
+ return 0;
}

void __wait_on_inode(struct inode *inode)
{
- DECLARE_WAITQUEUE(wait, current);
- wait_queue_head_t *wq = i_waitq_head(inode);
-
- add_wait_queue(wq, &wait);
-repeat:
- set_current_state(TASK_UNINTERRUPTIBLE);
- if (inode->i_state & I_LOCK) {
- schedule();
- goto repeat;
- }
- remove_wait_queue(wq, &wait);
- __set_current_state(TASK_RUNNING);
+ wait_on_bit(&inode->i_state, __I_LOCK, inode_wait, TASK_UNINTERRUPTIBLE);
}

/*
@@ -1305,27 +1285,23 @@
*/
static void __wait_on_freeing_inode(struct inode *inode)
{
- DECLARE_WAITQUEUE(wait, current);
- wait_queue_head_t *wq = i_waitq_head(inode);
+ wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_LOCK);
+ DEFINE_WAIT_BIT(wait, &inode->i_state, __I_LOCK);

- add_wait_queue(wq, &wait);
- set_current_state(TASK_UNINTERRUPTIBLE);
+ prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
spin_unlock(&inode_lock);
schedule();
- remove_wait_queue(wq, &wait);
+ finish_wait(wq, &wait.wait);
spin_lock(&inode_lock);
}

void wake_up_inode(struct inode *inode)
{
- wait_queue_head_t *wq = i_waitq_head(inode);
-
/*
* Prevent speculative execution through spin_unlock(&inode_lock);
*/
smp_mb();
- if (waitqueue_active(wq))
- wake_up_all(wq);
+ wake_up_bit(&inode->i_state, __I_LOCK);
}
EXPORT_SYMBOL(wake_up_inode);

@@ -1361,11 +1337,6 @@

void __init inode_init(unsigned long mempages)
{
- int i;
-
- for (i = 0; i < ARRAY_SIZE(i_wait_queue_heads); i++)
- init_waitqueue_head(&i_wait_queue_heads[i].wqh);
-
/* inode slab cache */
inode_cachep = kmem_cache_create("inode_cache", sizeof(struct inode),
0, SLAB_PANIC, init_once, NULL);