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btrfs: zoned: optimize hint byte for zoned allocator

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Writing sequentially to a huge file on btrfs on a SMR HDD revealed a
decline of the performance (220 MiB/s to 30 MiB/s after 500 minutes).

The performance goes down because of increased latency of the extent
allocation, which is induced by a traversing of a lot of full block groups.

So, this patch optimizes the ffe_ctl->hint_byte by choosing a block group
with sufficient size from the active block group list, which does not
contain full block groups.

After applying the patch, the performance is maintained well.

Fixes: 2eda57089e ("btrfs: zoned: implement sequential extent allocation")
CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Naohiro Aota 2023-12-19 01:02:29 +09:00 committed by David Sterba
parent b271fee9a4
commit 02444f2ac2
1 changed files with 18 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

18
fs/btrfs/extent-tree.c
View file

@ -4311,6 +4311,24 @@ static int prepare_allocation_zoned(struct btrfs_fs_info *fs_info,
if (fs_info->data_reloc_bg)
ffe_ctl->hint_byte = fs_info->data_reloc_bg;
spin_unlock(&fs_info->relocation_bg_lock);
} else if (ffe_ctl->flags & BTRFS_BLOCK_GROUP_DATA) {
struct btrfs_block_group *block_group;
spin_lock(&fs_info->zone_active_bgs_lock);
list_for_each_entry(block_group, &fs_info->zone_active_bgs, active_bg_list) {
/*
* No lock is OK here because avail is monotinically
* decreasing, and this is just a hint.
*/
u64 avail = block_group->zone_capacity - block_group->alloc_offset;
if (block_group_bits(block_group, ffe_ctl->flags) &&
avail >= ffe_ctl->num_bytes) {
ffe_ctl->hint_byte = block_group->start;
break;
}
}
spin_unlock(&fs_info->zone_active_bgs_lock);
}
return 0;