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author | Chris Mason <chris.mason@oracle.com> | 2008-07-31 23:42:53 +0400 |
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committer | Chris Mason <chris.mason@oracle.com> | 2008-09-25 19:04:05 +0400 |
commit | 61b4944018449003ac5f9757f4d125dce519cf51 (patch) | |
tree | 553855996c641a945344db870b6dfd0d2d02086e /fs/btrfs/file-item.c | |
parent | 37d1aeee3990385e9bb436c50c2f7e120a668df6 (diff) | |
download | linux-61b4944018449003ac5f9757f4d125dce519cf51.tar.xz |
Btrfs: Fix streaming read performance with checksumming on
Large streaming reads make for large bios, which means each entry on the
list async work queues represents a large amount of data. IO
congestion throttling on the device was kicking in before the async
worker threads decided a single thread was busy and needed some help.
The end result was that a streaming read would result in a single CPU
running at 100% instead of balancing the work off to other CPUs.
This patch also changes the pre-IO checksum lookup done by reads to
work on a per-bio basis instead of a per-page. This results in many
extra btree lookups on large streaming reads. Doing the checksum lookup
right before bio submit allows us to reuse searches while processing
adjacent offsets.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/file-item.c')
-rw-r--r-- | fs/btrfs/file-item.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c index 2311061f070e..a5ff19b34b21 100644 --- a/fs/btrfs/file-item.c +++ b/fs/btrfs/file-item.c @@ -134,6 +134,83 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans, return ret; } +int btrfs_lookup_bio_sums(struct btrfs_root *root, struct inode *inode, + struct bio *bio) +{ + u32 sum; + struct bio_vec *bvec = bio->bi_io_vec; + int bio_index = 0; + u64 offset; + u64 item_start_offset = 0; + u64 item_last_offset = 0; + u32 diff; + int ret; + struct btrfs_path *path; + struct btrfs_csum_item *item = NULL; + struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; + + path = btrfs_alloc_path(); + path->reada = 2; + + WARN_ON(bio->bi_vcnt <= 0); + + while(bio_index < bio->bi_vcnt) { + offset = page_offset(bvec->bv_page) + bvec->bv_offset; + ret = btrfs_find_ordered_sum(inode, offset, &sum); + if (ret == 0) + goto found; + + if (!item || offset < item_start_offset || + offset >= item_last_offset) { + struct btrfs_key found_key; + u32 item_size; + + if (item) + btrfs_release_path(root, path); + item = btrfs_lookup_csum(NULL, root, path, + inode->i_ino, offset, 0); + if (IS_ERR(item)) { + ret = PTR_ERR(item); + if (ret == -ENOENT || ret == -EFBIG) + ret = 0; + sum = 0; + printk("no csum found for inode %lu start " + "%llu\n", inode->i_ino, + (unsigned long long)offset); + goto found; + } + btrfs_item_key_to_cpu(path->nodes[0], &found_key, + path->slots[0]); + + item_start_offset = found_key.offset; + item_size = btrfs_item_size_nr(path->nodes[0], + path->slots[0]); + item_last_offset = item_start_offset + + (item_size / BTRFS_CRC32_SIZE) * + root->sectorsize; + item = btrfs_item_ptr(path->nodes[0], path->slots[0], + struct btrfs_csum_item); + } + /* + * this byte range must be able to fit inside + * a single leaf so it will also fit inside a u32 + */ + diff = offset - item_start_offset; + diff = diff / root->sectorsize; + diff = diff * BTRFS_CRC32_SIZE; + + read_extent_buffer(path->nodes[0], &sum, + (unsigned long)item + diff, + BTRFS_CRC32_SIZE); +found: + set_state_private(io_tree, offset, sum); + bio_index++; + bvec++; + } + btrfs_free_path(path); + return 0; +} + int btrfs_csum_one_bio(struct btrfs_root *root, struct inode *inode, struct bio *bio) { |