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authorFilipe Manana <fdmanana@suse.com>2022-02-03 14:55:50 +0000
committerDavid Sterba <dsterba@suse.com>2022-03-14 13:13:50 +0100
commite1f53ed874e2f242e7009c3123f9776c5aec61c3 (patch)
treee8b7d02cb3d7430fd36d527dc1114fc7b1150b7e /fs/btrfs/tree-log.c
parentd84575317078239ad2835bc42fb4d2d96ab51646 (diff)
btrfs: prepare extents to be logged before locking a log tree path
When we want to log an extent, in the fast fsync path, we obtain a path to the leaf that will hold the file extent item either through a deletion search, via btrfs_drop_extents(), or through an insertion search using btrfs_insert_empty_item(). After that we fill the file extent item's fields one by one directly on the leaf. Instead of doing that, we could prepare the file extent item before obtaining a btree path, and then copy the prepared extent item with a single operation once we get the path. This helps avoid some contention on the log tree, since we are holding write locks for longer than necessary, especially in the case where the path is obtained via btrfs_drop_extents() through a deletion search, which always keeps a write lock on the nodes at levels 1 and 2 (besides the leaf). This change does that, we prepare the file extent item that is going to be inserted before acquiring a path, and then copy it into a leaf using a single copy operation once we get a path. This change if part of a patchset that is comprised of the following patches: 1/6 btrfs: remove unnecessary leaf free space checks when pushing items 2/6 btrfs: avoid unnecessary COW of leaves when deleting items from a leaf 3/6 btrfs: avoid unnecessary computation when deleting items from a leaf 4/6 btrfs: remove constraint on number of visited leaves when replacing extents 5/6 btrfs: remove useless path release in the fast fsync path 6/6 btrfs: prepare extents to be logged before locking a log tree path The following test was run to measure the impact of the whole patchset: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi MOUNT_OPTIONS="-o ssd" MKFS_OPTIONS="-R free-space-tree -O no-holes" NUM_JOBS=8 FILE_SIZE=128M RUN_TIME=200 cat <<EOF > /tmp/fio-job.ini [writers] rw=randwrite fsync=1 fallocate=none group_reporting=1 direct=0 bssplit=4k/20:8k/20:16k/20:32k/10:64k/10:128k/5:256k/5:512k/5:1m/5 ioengine=sync filesize=$FILE_SIZE runtime=$RUN_TIME time_based directory=$MNT numjobs=$NUM_JOBS thread EOF echo "performance" | \ tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor echo echo "Using config:" echo cat /tmp/fio-job.ini echo umount $MNT &> /dev/null mkfs.btrfs -f $MKFS_OPTIONS $DEV mount $MOUNT_OPTIONS $DEV $MNT fio /tmp/fio-job.ini umount $MNT The test ran inside a VM (8 cores, 32G of RAM) with the target disk mapping to a raw NVMe device, and using a non-debug kernel config (Debian's default config). Before the patchset: WRITE: bw=116MiB/s (122MB/s), 116MiB/s-116MiB/s (122MB/s-122MB/s), io=22.7GiB (24.4GB), run=200013-200013msec After the patchset: WRITE: bw=125MiB/s (131MB/s), 125MiB/s-125MiB/s (131MB/s-131MB/s), io=24.3GiB (26.1GB), run=200007-200007msec A 7.8% gain on throughput and +7.0% more IO done in the same period of time (200 seconds). Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tree-log.c')
-rw-r--r--fs/btrfs/tree-log.c64
1 files changed, 27 insertions, 37 deletions
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 5b14339d269f..d5b7b565036d 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4675,14 +4675,34 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
{
struct btrfs_drop_extents_args drop_args = { 0 };
struct btrfs_root *log = inode->root->log_root;
- struct btrfs_file_extent_item *fi;
+ struct btrfs_file_extent_item fi = { 0 };
struct extent_buffer *leaf;
- struct btrfs_map_token token;
struct btrfs_key key;
u64 extent_offset = em->start - em->orig_start;
u64 block_len;
int ret;
+ btrfs_set_stack_file_extent_generation(&fi, trans->transid);
+ if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
+ btrfs_set_stack_file_extent_type(&fi, BTRFS_FILE_EXTENT_PREALLOC);
+ else
+ btrfs_set_stack_file_extent_type(&fi, BTRFS_FILE_EXTENT_REG);
+
+ block_len = max(em->block_len, em->orig_block_len);
+ if (em->compress_type != BTRFS_COMPRESS_NONE) {
+ btrfs_set_stack_file_extent_disk_bytenr(&fi, em->block_start);
+ btrfs_set_stack_file_extent_disk_num_bytes(&fi, block_len);
+ } else if (em->block_start < EXTENT_MAP_LAST_BYTE) {
+ btrfs_set_stack_file_extent_disk_bytenr(&fi, em->block_start -
+ extent_offset);
+ btrfs_set_stack_file_extent_disk_num_bytes(&fi, block_len);
+ }
+
+ btrfs_set_stack_file_extent_offset(&fi, extent_offset);
+ btrfs_set_stack_file_extent_num_bytes(&fi, em->len);
+ btrfs_set_stack_file_extent_ram_bytes(&fi, em->ram_bytes);
+ btrfs_set_stack_file_extent_compression(&fi, em->compress_type);
+
ret = log_extent_csums(trans, inode, log, em, ctx);
if (ret)
return ret;
@@ -4701,7 +4721,7 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
drop_args.start = em->start;
drop_args.end = em->start + em->len;
drop_args.replace_extent = true;
- drop_args.extent_item_size = sizeof(*fi);
+ drop_args.extent_item_size = sizeof(fi);
ret = btrfs_drop_extents(trans, log, inode, &drop_args);
if (ret)
return ret;
@@ -4713,44 +4733,14 @@ static int log_one_extent(struct btrfs_trans_handle *trans,
key.offset = em->start;
ret = btrfs_insert_empty_item(trans, log, path, &key,
- sizeof(*fi));
+ sizeof(fi));
if (ret)
return ret;
}
leaf = path->nodes[0];
- btrfs_init_map_token(&token, leaf);
- fi = btrfs_item_ptr(leaf, path->slots[0],
- struct btrfs_file_extent_item);
-
- btrfs_set_token_file_extent_generation(&token, fi, trans->transid);
- if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
- btrfs_set_token_file_extent_type(&token, fi,
- BTRFS_FILE_EXTENT_PREALLOC);
- else
- btrfs_set_token_file_extent_type(&token, fi,
- BTRFS_FILE_EXTENT_REG);
-
- block_len = max(em->block_len, em->orig_block_len);
- if (em->compress_type != BTRFS_COMPRESS_NONE) {
- btrfs_set_token_file_extent_disk_bytenr(&token, fi,
- em->block_start);
- btrfs_set_token_file_extent_disk_num_bytes(&token, fi, block_len);
- } else if (em->block_start < EXTENT_MAP_LAST_BYTE) {
- btrfs_set_token_file_extent_disk_bytenr(&token, fi,
- em->block_start -
- extent_offset);
- btrfs_set_token_file_extent_disk_num_bytes(&token, fi, block_len);
- } else {
- btrfs_set_token_file_extent_disk_bytenr(&token, fi, 0);
- btrfs_set_token_file_extent_disk_num_bytes(&token, fi, 0);
- }
-
- btrfs_set_token_file_extent_offset(&token, fi, extent_offset);
- btrfs_set_token_file_extent_num_bytes(&token, fi, em->len);
- btrfs_set_token_file_extent_ram_bytes(&token, fi, em->ram_bytes);
- btrfs_set_token_file_extent_compression(&token, fi, em->compress_type);
- btrfs_set_token_file_extent_encryption(&token, fi, 0);
- btrfs_set_token_file_extent_other_encoding(&token, fi, 0);
+ write_extent_buffer(leaf, &fi,
+ btrfs_item_ptr_offset(leaf, path->slots[0]),
+ sizeof(fi));
btrfs_mark_buffer_dirty(leaf);
btrfs_release_path(path);