diff options
| author | Darrick J. Wong <darrick.wong@oracle.com> | 2016-08-03 04:29:42 +0300 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2016-08-03 04:29:42 +0300 |
| commit | df3954ff72590fd20b68261a0c939e40fa3579ea (patch) | |
| tree | d8ebaf48b2e1a1a90bbddf2def6a2c650bcf5b1b | |
| parent | ba9e780246a15a35f8ebe5b60f4a11bb58e85bda (diff) | |
| download | linux-df3954ff72590fd20b68261a0c939e40fa3579ea.tar.xz | |
xfs: increase XFS_BTREE_MAXLEVELS to fit the rmapbt
By my calculations, a 1,073,741,824 block AG with a 1k block size
can attain a maximum height of 9. Assuming a record size of 24
bytes, a key/ptr size of 44 bytes, and half-full btree nodes, we'd
need 53,687,092 blocks for the records and ~6 million blocks for the
keys. That requires a btree of height 9 based on the following
derivation:
Block size = 1024b
sblock CRC header = 56b
== 1024-56 = 968 bytes for tree data
rmapbt record = 24b
== 40 records per leaf block
rmapbt ptr/key = 44b
== 22 ptr/keys per block
Worst case, each block is half full, so 20 records and 11 ptrs per block.
1073741824 rmap records / 20 records per block
== 53687092 leaf blocks
53687092 leaves / 11 ptrs per block
== 4880645 level 1 blocks
== 443695 level 2 blocks
== 40336 level 3 blocks
== 3667 level 4 blocks
== 334 level 5 blocks
== 31 level 6 blocks
== 3 level 7 blocks
== 1 level 8 block
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
| -rw-r--r-- | fs/xfs/libxfs/xfs_btree.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h index 154eefdcb730..ac5cd6ef6859 100644 --- a/fs/xfs/libxfs/xfs_btree.h +++ b/fs/xfs/libxfs/xfs_btree.h @@ -133,7 +133,7 @@ do { \ } \ } while (0) -#define XFS_BTREE_MAXLEVELS 8 /* max of all btrees */ +#define XFS_BTREE_MAXLEVELS 9 /* max of all btrees */ struct xfs_btree_ops { /* size of the key and record structures */ |