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Commit 2dd3e67b authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: More throttle tuning 



* Make walk_down_tree wake up throttled tasks more often
* Make walk_down_tree call cond_resched during long loops
* As the size of the ref cache grows, wait longer in throttle
* Get rid of the reada code in walk_down_tree, the leaves don't get
  read anymore, thanks to the ref cache.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 65b51a00

fs/btrfs/disk-io.c

+2 −11
Original line number Diff line number Diff line
@@ -188,13 +188,6 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, 
	btrfs_csum_final(crc, result);



	if (verify) {

		int from_this_trans = 0;



		if (root->fs_info->running_transaction &&

		    btrfs_header_generation(buf) ==

		    root->fs_info->running_transaction->transid)

			from_this_trans = 1;



		/* FIXME, this is not good */

		if (memcmp_extent_buffer(buf, result, 0, BTRFS_CRC32_SIZE)) {

			u32 val;
@@ -203,11 +196,9 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, 


			read_extent_buffer(buf, &val, 0, BTRFS_CRC32_SIZE);

			printk("btrfs: %s checksum verify failed on %llu "

			       "wanted %X found %X from_this_trans %d "

			       "level %d\n",

			       "wanted %X found %X level %d\n",

			       root->fs_info->sb->s_id,

			       buf->start, val, found, from_this_trans,

			       btrfs_header_level(buf));

			       buf->start, val, found, btrfs_header_level(buf));

			return 1;

		}

	} else {

fs/btrfs/extent-tree.c

+12 −47
Original line number Diff line number Diff line
@@ -2369,6 +2369,11 @@ static int noinline drop_leaf_ref_no_cache(struct btrfs_trans_handle *trans, 
				leaf_owner, leaf_generation,

				key.objectid, key.offset, 0);

		mutex_unlock(&root->fs_info->alloc_mutex);



		atomic_inc(&root->fs_info->throttle_gen);

		wake_up(&root->fs_info->transaction_throttle);

		cond_resched();



		BUG_ON(ret);

	}

	return 0;
@@ -2389,6 +2394,11 @@ static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans, 
					ref->owner, ref->generation,

					info->objectid, info->offset, 0);

		mutex_unlock(&root->fs_info->alloc_mutex);



		atomic_inc(&root->fs_info->throttle_gen);

		wake_up(&root->fs_info->transaction_throttle);

		cond_resched();



		BUG_ON(ret);

		info++;

	}
@@ -2396,51 +2406,6 @@ static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans, 
	return 0;

}



static void noinline reada_walk_down(struct btrfs_root *root,

				     struct extent_buffer *node,

				     int slot)

{

	u64 bytenr;

	u64 last = 0;

	u32 nritems;

	u32 refs;

	u32 blocksize;

	int ret;

	int i;

	int level;

	int skipped = 0;



	nritems = btrfs_header_nritems(node);

	level = btrfs_header_level(node);

	if (level)

		return;



	for (i = slot; i < nritems && skipped < 32; i++) {

		bytenr = btrfs_node_blockptr(node, i);

		if (last && ((bytenr > last && bytenr - last > 32 * 1024) ||

			     (last > bytenr && last - bytenr > 32 * 1024))) {

			skipped++;

			continue;

		}

		blocksize = btrfs_level_size(root, level - 1);

		if (i != slot) {

			ret = lookup_extent_ref(NULL, root, bytenr,

						blocksize, &refs);

			BUG_ON(ret);

			if (refs != 1) {

				skipped++;

				continue;

			}

		}

		ret = readahead_tree_block(root, bytenr, blocksize,

					   btrfs_node_ptr_generation(node, i));

		last = bytenr + blocksize;

		cond_resched();

		if (ret)

			break;

	}

}



int drop_snap_lookup_refcount(struct btrfs_root *root, u64 start, u64 len,

			      u32 *refs)

{
@@ -2549,6 +2514,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, 


			atomic_inc(&root->fs_info->throttle_gen);

			wake_up(&root->fs_info->transaction_throttle);

			cond_resched();



			continue;

		}
@@ -2578,8 +2544,6 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, 
		if (!next || !btrfs_buffer_uptodate(next, ptr_gen)) {

			free_extent_buffer(next);



			if (path->slots[*level] == 0)

				reada_walk_down(root, cur, path->slots[*level]);

			next = read_tree_block(root, bytenr, blocksize,

					       ptr_gen);

			cond_resched();
@@ -2601,6 +2565,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, 
		path->nodes[*level-1] = next;

		*level = btrfs_header_level(next);

		path->slots[*level] = 0;

		cond_resched();

	}

out:

	WARN_ON(*level < 0);

fs/btrfs/transaction.c

+15 −0
Original line number Diff line number Diff line
@@ -210,7 +210,9 @@ static noinline int wait_for_commit(struct btrfs_root *root, 
static void throttle_on_drops(struct btrfs_root *root)

{

	struct btrfs_fs_info *info = root->fs_info;

	int harder_count = 0;



harder:

	if (atomic_read(&info->throttles)) {

		DEFINE_WAIT(wait);

		int thr;
@@ -226,6 +228,19 @@ static void throttle_on_drops(struct btrfs_root *root) 
			schedule();

			finish_wait(&info->transaction_throttle, &wait);

		} while (thr == atomic_read(&info->throttle_gen));

		harder_count++;



		if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&

		    harder_count < 2)

			goto harder;



		if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&

		    harder_count < 10)

			goto harder;



		if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&

		    harder_count < 20)

			goto harder;

	}

}