Commit db161806 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: account ticket size at add/delete time 



Instead of iterating all pending tickets on the normal/priority list to
sum their total size the cost can be amortized across ticket addition/
removal. This turns O(n) + O(m) (where n is the size of the normal list
and m of the priority list) into O(1). This will mostly have effect in
workloads that experience heavy flushing.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f8e66081

fs/btrfs/space-info.c

+6 −6
Original line number Diff line number Diff line
@@ -389,6 +389,8 @@ again: 
							      space_info,

							      ticket->bytes);

			list_del_init(&ticket->list);

			ASSERT(space_info->reclaim_size >= ticket->bytes);

			space_info->reclaim_size -= ticket->bytes;

			ticket->bytes = 0;

			space_info->tickets_id++;

			wake_up(&ticket->wait);
@@ -784,16 +786,12 @@ static inline u64 
btrfs_calc_reclaim_metadata_size(struct btrfs_fs_info *fs_info,

				 struct btrfs_space_info *space_info)

{

	struct reserve_ticket *ticket;

	u64 used;

	u64 avail;

	u64 expected;

	u64 to_reclaim = 0;

	u64 to_reclaim = space_info->reclaim_size;



	list_for_each_entry(ticket, &space_info->tickets, list)

		to_reclaim += ticket->bytes;

	list_for_each_entry(ticket, &space_info->priority_tickets, list)

		to_reclaim += ticket->bytes;

	lockdep_assert_held(&space_info->lock);



	avail = calc_available_free_space(fs_info, space_info,

					  BTRFS_RESERVE_FLUSH_ALL);
@@ -1192,8 +1190,10 @@ static int __reserve_metadata_bytes(struct btrfs_fs_info *fs_info, 
	 * the list and we will do our own flushing further down.

	 */

	if (ret && flush != BTRFS_RESERVE_NO_FLUSH) {

		ASSERT(space_info->reclaim_size >= 0);

		ticket.bytes = orig_bytes;

		ticket.error = 0;

		space_info->reclaim_size += ticket.bytes;

		init_waitqueue_head(&ticket.wait);

		if (flush == BTRFS_RESERVE_FLUSH_ALL) {

			list_add_tail(&ticket.list, &space_info->tickets);

fs/btrfs/space-info.h

+7 −0
Original line number Diff line number Diff line
@@ -54,6 +54,13 @@ struct btrfs_space_info { 
	struct list_head ro_bgs;

	struct list_head priority_tickets;

	struct list_head tickets;



	/*

	 * Size of space that needs to be reclaimed in order to satisfy pending

	 * tickets

	 */

	u64 reclaim_size;



	/*

	 * tickets_id just indicates the next ticket will be handled, so note

	 * it's not stored per ticket.

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