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6b06dd5a97
The disk space map stores it's index entries in a btree, these are accessed very frequently, so having a few cached makes a big difference to performance. With this change provisioning a new block takes roughly 20% less cpu. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
145 lines
4.1 KiB
C
145 lines
4.1 KiB
C
/*
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* Copyright (C) 2011 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#ifndef DM_SPACE_MAP_COMMON_H
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#define DM_SPACE_MAP_COMMON_H
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#include "dm-btree.h"
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/*----------------------------------------------------------------*/
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/*
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* Low level disk format
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*
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* Bitmap btree
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* ------------
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*
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* Each value stored in the btree is an index_entry. This points to a
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* block that is used as a bitmap. Within the bitmap hold 2 bits per
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* entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
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* REF_COUNT = many.
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*
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* Refcount btree
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* --------------
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*
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* Any entry that has a ref count higher than 2 gets entered in the ref
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* count tree. The leaf values for this tree is the 32-bit ref count.
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*/
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struct disk_index_entry {
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__le64 blocknr;
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__le32 nr_free;
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__le32 none_free_before;
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} __attribute__ ((packed, aligned(8)));
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#define MAX_METADATA_BITMAPS 255
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struct disk_metadata_index {
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__le32 csum;
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__le32 padding;
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__le64 blocknr;
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struct disk_index_entry index[MAX_METADATA_BITMAPS];
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} __attribute__ ((packed, aligned(8)));
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struct ll_disk;
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typedef int (*load_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *result);
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typedef int (*save_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *ie);
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typedef int (*init_index_fn)(struct ll_disk *ll);
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typedef int (*open_index_fn)(struct ll_disk *ll);
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typedef dm_block_t (*max_index_entries_fn)(struct ll_disk *ll);
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typedef int (*commit_fn)(struct ll_disk *ll);
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/*
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* A lot of time can be wasted reading and writing the same
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* index entry. So we cache a few entries.
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*/
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#define IE_CACHE_SIZE 64
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#define IE_CACHE_MASK (IE_CACHE_SIZE - 1)
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struct ie_cache {
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bool valid;
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bool dirty;
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dm_block_t index;
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struct disk_index_entry ie;
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};
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struct ll_disk {
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struct dm_transaction_manager *tm;
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struct dm_btree_info bitmap_info;
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struct dm_btree_info ref_count_info;
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uint32_t block_size;
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uint32_t entries_per_block;
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dm_block_t nr_blocks;
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dm_block_t nr_allocated;
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/*
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* bitmap_root may be a btree root or a simple index.
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*/
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dm_block_t bitmap_root;
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dm_block_t ref_count_root;
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struct disk_metadata_index mi_le;
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load_ie_fn load_ie;
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save_ie_fn save_ie;
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init_index_fn init_index;
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open_index_fn open_index;
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max_index_entries_fn max_entries;
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commit_fn commit;
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bool bitmap_index_changed:1;
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struct ie_cache ie_cache[IE_CACHE_SIZE];
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};
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struct disk_sm_root {
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__le64 nr_blocks;
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__le64 nr_allocated;
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__le64 bitmap_root;
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__le64 ref_count_root;
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} __attribute__ ((packed, aligned(8)));
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#define ENTRIES_PER_BYTE 4
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struct disk_bitmap_header {
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__le32 csum;
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__le32 not_used;
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__le64 blocknr;
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} __attribute__ ((packed, aligned(8)));
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/*----------------------------------------------------------------*/
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int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
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int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
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int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
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int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
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dm_block_t end, dm_block_t *result);
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int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
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dm_block_t begin, dm_block_t end, dm_block_t *result);
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/*
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* The next three functions return (via nr_allocations) the net number of
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* allocations that were made. This number may be negative if there were
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* more frees than allocs.
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*/
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int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, int32_t *nr_allocations);
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int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
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int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
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int sm_ll_commit(struct ll_disk *ll);
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int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
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int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
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void *root_le, size_t len);
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int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
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int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
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void *root_le, size_t len);
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/*----------------------------------------------------------------*/
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#endif /* DM_SPACE_MAP_COMMON_H */
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