![Miao Xie](/assets/img/avatar_default.png)
By the current code, if the requested size is very large, and all the extents in the free space cache are small, we will waste lots of the cpu time to cut the requested size in half and search the cache again and again until it gets down to the size the allocator can return. In fact, we can know the max extent size in the cache after the first search, so we needn't cut the size in half repeatedly, and just use the max extent size directly. This way can save lots of cpu time and make the performance grow up when there are only fragments in the free space cache. According to my test, if there are only 4KB free space extents in the fs, and the total size of those extents are 256MB, we can reduce the execute time of the following test from 5.4s to 1.4s. dd if=/dev/zero of=<testfile> bs=1MB count=1 oflag=sync Changelog v2 -> v3: - fix the problem that we skip the block group with the space which is less than we need. Changelog v1 -> v2: - address the problem that we return a wrong start position when searching the free space in a bitmap. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
125 lines
4.5 KiB
C
125 lines
4.5 KiB
C
/*
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* Copyright (C) 2009 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_FREE_SPACE_CACHE
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#define __BTRFS_FREE_SPACE_CACHE
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struct btrfs_free_space {
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struct rb_node offset_index;
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u64 offset;
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u64 bytes;
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unsigned long *bitmap;
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struct list_head list;
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};
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struct btrfs_free_space_ctl {
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spinlock_t tree_lock;
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struct rb_root free_space_offset;
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u64 free_space;
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int extents_thresh;
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int free_extents;
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int total_bitmaps;
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int unit;
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u64 start;
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struct btrfs_free_space_op *op;
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void *private;
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};
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struct btrfs_free_space_op {
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void (*recalc_thresholds)(struct btrfs_free_space_ctl *ctl);
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bool (*use_bitmap)(struct btrfs_free_space_ctl *ctl,
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struct btrfs_free_space *info);
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};
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struct inode *lookup_free_space_inode(struct btrfs_root *root,
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struct btrfs_block_group_cache
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*block_group, struct btrfs_path *path);
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int create_free_space_inode(struct btrfs_root *root,
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struct btrfs_trans_handle *trans,
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struct btrfs_block_group_cache *block_group,
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struct btrfs_path *path);
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int btrfs_check_trunc_cache_free_space(struct btrfs_root *root,
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struct btrfs_block_rsv *rsv);
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int btrfs_truncate_free_space_cache(struct btrfs_root *root,
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struct btrfs_trans_handle *trans,
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struct btrfs_path *path,
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struct inode *inode);
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int load_free_space_cache(struct btrfs_fs_info *fs_info,
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struct btrfs_block_group_cache *block_group);
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int btrfs_write_out_cache(struct btrfs_root *root,
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struct btrfs_trans_handle *trans,
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struct btrfs_block_group_cache *block_group,
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struct btrfs_path *path);
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struct inode *lookup_free_ino_inode(struct btrfs_root *root,
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struct btrfs_path *path);
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int create_free_ino_inode(struct btrfs_root *root,
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struct btrfs_trans_handle *trans,
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struct btrfs_path *path);
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int load_free_ino_cache(struct btrfs_fs_info *fs_info,
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struct btrfs_root *root);
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int btrfs_write_out_ino_cache(struct btrfs_root *root,
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struct btrfs_trans_handle *trans,
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struct btrfs_path *path);
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void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group);
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int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,
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u64 bytenr, u64 size);
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static inline int
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btrfs_add_free_space(struct btrfs_block_group_cache *block_group,
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u64 bytenr, u64 size)
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{
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return __btrfs_add_free_space(block_group->free_space_ctl,
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bytenr, size);
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}
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int btrfs_remove_free_space(struct btrfs_block_group_cache *block_group,
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u64 bytenr, u64 size);
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void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl);
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void btrfs_remove_free_space_cache(struct btrfs_block_group_cache
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*block_group);
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u64 btrfs_find_space_for_alloc(struct btrfs_block_group_cache *block_group,
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u64 offset, u64 bytes, u64 empty_size,
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u64 *max_extent_size);
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u64 btrfs_find_ino_for_alloc(struct btrfs_root *fs_root);
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void btrfs_dump_free_space(struct btrfs_block_group_cache *block_group,
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u64 bytes);
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int btrfs_find_space_cluster(struct btrfs_root *root,
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struct btrfs_block_group_cache *block_group,
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struct btrfs_free_cluster *cluster,
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u64 offset, u64 bytes, u64 empty_size);
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void btrfs_init_free_cluster(struct btrfs_free_cluster *cluster);
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u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
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struct btrfs_free_cluster *cluster, u64 bytes,
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u64 min_start, u64 *max_extent_size);
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int btrfs_return_cluster_to_free_space(
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struct btrfs_block_group_cache *block_group,
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struct btrfs_free_cluster *cluster);
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int btrfs_trim_block_group(struct btrfs_block_group_cache *block_group,
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u64 *trimmed, u64 start, u64 end, u64 minlen);
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/* Support functions for runnint our sanity tests */
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#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
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int test_add_free_space_entry(struct btrfs_block_group_cache *cache,
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u64 offset, u64 bytes, bool bitmap);
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int test_check_exists(struct btrfs_block_group_cache *cache,
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u64 offset, u64 bytes);
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#endif
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#endif
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