diff options
author | David Sterba <dsterba@suse.com> | 2020-07-02 10:54:11 +0200 |
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committer | David Sterba <dsterba@suse.com> | 2020-12-08 15:53:58 +0100 |
commit | fe5ecbe818de38774895305e1f2d48972f1b745f (patch) | |
tree | 098ab0742863dee92a57cc1dc3cf6bb6c624cb06 /fs/btrfs/ctree.h | |
parent | 22b6331d961712ac2735423e5a6c04e9d0fd7897 (diff) | |
download | linux-fe5ecbe818de38774895305e1f2d48972f1b745f.tar.bz2 |
btrfs: precalculate checksums per leaf once
btrfs_csum_bytes_to_leaves shows up in system profiles, which makes it a
candidate for optimizations. After the 64bit division has been replaced
by shift, there's still a calculation done each time the function is
called: checksums per leaf.
As this is a constant value for the entire filesystem lifetime, we
can calculate it once at mount time and reuse. This also allows to
reduce the division to 64bit/32bit as we know the constant will always
fit the 32bit type.
Replace the open-coded rounding up with a macro that internally handles
the 64bit division and as it's now a short function, make it static
inline (slight code increase, slight stack usage reduction).
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/ctree.h')
-rw-r--r-- | fs/btrfs/ctree.h | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 3d06596b8746..f28960647c01 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -938,6 +938,7 @@ struct btrfs_fs_info { /* ilog2 of sectorsize, use to avoid 64bit division */ u32 sectorsize_bits; u32 csum_size; + u32 csums_per_leaf; u32 stripesize; /* Block groups and devices containing active swapfiles. */ @@ -2525,7 +2526,17 @@ int btrfs_get_extent_inline_ref_type(const struct extent_buffer *eb, enum btrfs_inline_ref_type is_data); u64 hash_extent_data_ref(u64 root_objectid, u64 owner, u64 offset); -u64 btrfs_csum_bytes_to_leaves(struct btrfs_fs_info *fs_info, u64 csum_bytes); +/* + * Take the number of bytes to be checksummmed and figure out how many leaves + * it would require to store the csums for that many bytes. + */ +static inline u64 btrfs_csum_bytes_to_leaves( + const struct btrfs_fs_info *fs_info, u64 csum_bytes) +{ + const u64 num_csums = csum_bytes >> fs_info->sectorsize_bits; + + return DIV_ROUND_UP_ULL(num_csums, fs_info->csums_per_leaf); +} /* * Use this if we would be adding new items, as we could split nodes as we cow |