Commit 85e79ec7 authored by Naohiro Aota's avatar Naohiro Aota Committed by David Sterba
Browse files

btrfs: zoned: enable metadata over-commit for non-ZNS setup 



The commit 79417d04 ("btrfs: zoned: disable metadata overcommit for
zoned") disabled the metadata over-commit to track active zones properly.

However, it also introduced a heavy overhead by allocating new metadata
block groups and/or flushing dirty buffers to release the space
reservations. Specifically, a workload (write only without any sync
operations) worsen its performance from 343.77 MB/sec (v5.19) to 182.89
MB/sec (v6.0).

The performance is still bad on current misc-next which is 187.95 MB/sec.
And, with this patch applied, it improves back to 326.70 MB/sec (+73.82%).

This patch introduces a new fs_info->flag BTRFS_FS_NO_OVERCOMMIT to
indicate it needs to disable the metadata over-commit. The flag is enabled
when a device with max active zones limit is loaded into a file-system.

Fixes: 79417d04 ("btrfs: zoned: disable metadata overcommit for zoned")
CC: stable@vger.kernel.org # 6.0+
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: default avatarNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 75181406

fs/btrfs/fs.h

+6 −0
Original line number Diff line number Diff line
@@ -119,6 +119,12 @@ enum { 
	/* Indicate that we want to commit the transaction. */

	BTRFS_FS_NEED_TRANS_COMMIT,



	/*

	 * Indicate metadata over-commit is disabled. This is set when active

	 * zone tracking is needed.

	 */

	BTRFS_FS_NO_OVERCOMMIT,



#if BITS_PER_LONG == 32

	/* Indicate if we have error/warn message printed on 32bit systems */

	BTRFS_FS_32BIT_ERROR,

fs/btrfs/space-info.c

+2 −1
Original line number Diff line number Diff line
@@ -407,7 +407,8 @@ int btrfs_can_overcommit(struct btrfs_fs_info *fs_info, 
		return 0;



	used = btrfs_space_info_used(space_info, true);

	if (btrfs_is_zoned(fs_info) && (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))

	if (test_bit(BTRFS_FS_NO_OVERCOMMIT, &fs_info->flags) &&

	    (space_info->flags & BTRFS_BLOCK_GROUP_METADATA))

		avail = 0;

	else

		avail = calc_available_free_space(fs_info, space_info, flush);

fs/btrfs/zoned.c

+2 −0
Original line number Diff line number Diff line
@@ -539,6 +539,8 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache) 
		}

		atomic_set(&zone_info->active_zones_left,

			   max_active_zones - nactive);

		/* Overcommit does not work well with active zone tacking. */

		set_bit(BTRFS_FS_NO_OVERCOMMIT, &fs_info->flags);

	}



	/* Validate superblock log */