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authorChris Mason <chris.mason@fusionio.com>2013-03-04 17:13:31 -0500
committerChris Mason <chris.mason@fusionio.com>2013-03-07 07:52:40 -0500
commitde3cb945db4d8eb3b046dc7a5ea89a893372750c (patch)
treed3f479c1431a2607d7154d7a1e10878533d38008
parent3a01aa7a25274308fe813a6237f678aed901cea3 (diff)
downloadvexpress-lsk-de3cb945db4d8eb3b046dc7a5ea89a893372750c.tar.gz
Btrfs: improve the delayed inode throttling
The delayed inode code batches up changes to the btree in hopes of doing them in bulk. As the changes build up, processes kick off worker threads and wait for them to make progress. The current code kicks off an async work queue item for each delayed node, which creates a lot of churn. It also uses a fixed 1 HZ waiting period for the throttle, which allows us to build a lot of pending work and can slow down the commit. This changes us to watch a sequence counter as it is bumped during the operations. We kick off fewer work items and have each work item do more work. Signed-off-by: Chris Mason <chris.mason@fusionio.com>
-rw-r--r--fs/btrfs/delayed-inode.c151
-rw-r--r--fs/btrfs/delayed-inode.h2
2 files changed, 92 insertions, 61 deletions
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 0b278b117cb..14fce27b478 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -22,8 +22,9 @@
#include "disk-io.h"
#include "transaction.h"
-#define BTRFS_DELAYED_WRITEBACK 400
-#define BTRFS_DELAYED_BACKGROUND 100
+#define BTRFS_DELAYED_WRITEBACK 512
+#define BTRFS_DELAYED_BACKGROUND 128
+#define BTRFS_DELAYED_BATCH 16
static struct kmem_cache *delayed_node_cache;
@@ -494,6 +495,15 @@ static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
BTRFS_DELAYED_DELETION_ITEM);
}
+static void finish_one_item(struct btrfs_delayed_root *delayed_root)
+{
+ int seq = atomic_inc_return(&delayed_root->items_seq);
+ if ((atomic_dec_return(&delayed_root->items) <
+ BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) &&
+ waitqueue_active(&delayed_root->wait))
+ wake_up(&delayed_root->wait);
+}
+
static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
{
struct rb_root *root;
@@ -512,10 +522,8 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
rb_erase(&delayed_item->rb_node, root);
delayed_item->delayed_node->count--;
- if (atomic_dec_return(&delayed_root->items) <
- BTRFS_DELAYED_BACKGROUND &&
- waitqueue_active(&delayed_root->wait))
- wake_up(&delayed_root->wait);
+
+ finish_one_item(delayed_root);
}
static void btrfs_release_delayed_item(struct btrfs_delayed_item *item)
@@ -1056,10 +1064,7 @@ static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
delayed_node->count--;
delayed_root = delayed_node->root->fs_info->delayed_root;
- if (atomic_dec_return(&delayed_root->items) <
- BTRFS_DELAYED_BACKGROUND &&
- waitqueue_active(&delayed_root->wait))
- wake_up(&delayed_root->wait);
+ finish_one_item(delayed_root);
}
}
@@ -1304,35 +1309,44 @@ void btrfs_remove_delayed_node(struct inode *inode)
btrfs_release_delayed_node(delayed_node);
}
-struct btrfs_async_delayed_node {
- struct btrfs_root *root;
- struct btrfs_delayed_node *delayed_node;
+struct btrfs_async_delayed_work {
+ struct btrfs_delayed_root *delayed_root;
+ int nr;
struct btrfs_work work;
};
-static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
+static void btrfs_async_run_delayed_root(struct btrfs_work *work)
{
- struct btrfs_async_delayed_node *async_node;
+ struct btrfs_async_delayed_work *async_work;
+ struct btrfs_delayed_root *delayed_root;
struct btrfs_trans_handle *trans;
struct btrfs_path *path;
struct btrfs_delayed_node *delayed_node = NULL;
struct btrfs_root *root;
struct btrfs_block_rsv *block_rsv;
- int need_requeue = 0;
+ int total_done = 0;
- async_node = container_of(work, struct btrfs_async_delayed_node, work);
+ async_work = container_of(work, struct btrfs_async_delayed_work, work);
+ delayed_root = async_work->delayed_root;
path = btrfs_alloc_path();
if (!path)
goto out;
- path->leave_spinning = 1;
- delayed_node = async_node->delayed_node;
+again:
+ if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND / 2)
+ goto free_path;
+
+ delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
+ if (!delayed_node)
+ goto free_path;
+
+ path->leave_spinning = 1;
root = delayed_node->root;
trans = btrfs_join_transaction(root);
if (IS_ERR(trans))
- goto free_path;
+ goto release_path;
block_rsv = trans->block_rsv;
trans->block_rsv = &root->fs_info->delayed_block_rsv;
@@ -1363,57 +1377,47 @@ static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
* Task1 will sleep until the transaction is commited.
*/
mutex_lock(&delayed_node->mutex);
- if (delayed_node->count)
- need_requeue = 1;
- else
- btrfs_dequeue_delayed_node(root->fs_info->delayed_root,
- delayed_node);
+ btrfs_dequeue_delayed_node(root->fs_info->delayed_root, delayed_node);
mutex_unlock(&delayed_node->mutex);
trans->block_rsv = block_rsv;
btrfs_end_transaction_dmeta(trans, root);
btrfs_btree_balance_dirty_nodelay(root);
+
+release_path:
+ btrfs_release_path(path);
+ total_done++;
+
+ btrfs_release_prepared_delayed_node(delayed_node);
+ if (async_work->nr == 0 || total_done < async_work->nr)
+ goto again;
+
free_path:
btrfs_free_path(path);
out:
- if (need_requeue)
- btrfs_requeue_work(&async_node->work);
- else {
- btrfs_release_prepared_delayed_node(delayed_node);
- kfree(async_node);
- }
+ wake_up(&delayed_root->wait);
+ kfree(async_work);
}
+
static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,
- struct btrfs_root *root, int all)
+ struct btrfs_root *root, int nr)
{
- struct btrfs_async_delayed_node *async_node;
- struct btrfs_delayed_node *curr;
- int count = 0;
+ struct btrfs_async_delayed_work *async_work;
-again:
- curr = btrfs_first_prepared_delayed_node(delayed_root);
- if (!curr)
+ if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
return 0;
- async_node = kmalloc(sizeof(*async_node), GFP_NOFS);
- if (!async_node) {
- btrfs_release_prepared_delayed_node(curr);
+ async_work = kmalloc(sizeof(*async_work), GFP_NOFS);
+ if (!async_work)
return -ENOMEM;
- }
-
- async_node->root = root;
- async_node->delayed_node = curr;
-
- async_node->work.func = btrfs_async_run_delayed_node_done;
- async_node->work.flags = 0;
- btrfs_queue_worker(&root->fs_info->delayed_workers, &async_node->work);
- count++;
-
- if (all || count < 4)
- goto again;
+ async_work->delayed_root = delayed_root;
+ async_work->work.func = btrfs_async_run_delayed_root;
+ async_work->work.flags = 0;
+ async_work->nr = nr;
+ btrfs_queue_worker(&root->fs_info->delayed_workers, &async_work->work);
return 0;
}
@@ -1424,30 +1428,55 @@ void btrfs_assert_delayed_root_empty(struct btrfs_root *root)
WARN_ON(btrfs_first_delayed_node(delayed_root));
}
+static int refs_newer(struct btrfs_delayed_root *delayed_root,
+ int seq, int count)
+{
+ int val = atomic_read(&delayed_root->items_seq);
+
+ if (val < seq || val >= seq + count)
+ return 1;
+ return 0;
+}
+
void btrfs_balance_delayed_items(struct btrfs_root *root)
{
struct btrfs_delayed_root *delayed_root;
+ int seq;
delayed_root = btrfs_get_delayed_root(root);
if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
return;
+ seq = atomic_read(&delayed_root->items_seq);
+
if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {
int ret;
- ret = btrfs_wq_run_delayed_node(delayed_root, root, 1);
+ DEFINE_WAIT(__wait);
+
+ ret = btrfs_wq_run_delayed_node(delayed_root, root, 0);
if (ret)
return;
- wait_event_interruptible_timeout(
- delayed_root->wait,
- (atomic_read(&delayed_root->items) <
- BTRFS_DELAYED_BACKGROUND),
- HZ);
- return;
+ while (1) {
+ prepare_to_wait(&delayed_root->wait, &__wait,
+ TASK_INTERRUPTIBLE);
+
+ if (refs_newer(delayed_root, seq,
+ BTRFS_DELAYED_BATCH) ||
+ atomic_read(&delayed_root->items) <
+ BTRFS_DELAYED_BACKGROUND) {
+ break;
+ }
+ if (!signal_pending(current))
+ schedule();
+ else
+ break;
+ }
+ finish_wait(&delayed_root->wait, &__wait);
}
- btrfs_wq_run_delayed_node(delayed_root, root, 0);
+ btrfs_wq_run_delayed_node(delayed_root, root, BTRFS_DELAYED_BATCH);
}
/* Will return 0 or -ENOMEM */
diff --git a/fs/btrfs/delayed-inode.h b/fs/btrfs/delayed-inode.h
index 78b6ad0fc66..1d5c5f7abe3 100644
--- a/fs/btrfs/delayed-inode.h
+++ b/fs/btrfs/delayed-inode.h
@@ -43,6 +43,7 @@ struct btrfs_delayed_root {
*/
struct list_head prepare_list;
atomic_t items; /* for delayed items */
+ atomic_t items_seq; /* for delayed items */
int nodes; /* for delayed nodes */
wait_queue_head_t wait;
};
@@ -86,6 +87,7 @@ static inline void btrfs_init_delayed_root(
struct btrfs_delayed_root *delayed_root)
{
atomic_set(&delayed_root->items, 0);
+ atomic_set(&delayed_root->items_seq, 0);
delayed_root->nodes = 0;
spin_lock_init(&delayed_root->lock);
init_waitqueue_head(&delayed_root->wait);