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| author |   Josef Bacik <jbacik@fb.com> | 2015-09-23 17:11:16 -0400 |
|---|---|---|
| committer |   Chris Mason <clm@fb.com> | 2015-10-21 18:51:44 -0700 |
| commit | 0b670dc44c91bd1e5fac15b5ac4c98c8bd255ca2 (patch) | |
| tree | e0215055573cac5f67c6f6c5a515efdceb60bb07 /fs/btrfs/inode.c | |
| parent | Btrfs: add fragment=* debug mount option (diff) | |
| download | linux-dev-0b670dc44c91bd1e5fac15b5ac4c98c8bd255ca2.tar.xz linux-dev-0b670dc44c91bd1e5fac15b5ac4c98c8bd255ca2.zip | |
Btrfs: fix prealloc under heavy fragmentation conditions
If we are heavily fragmented we will continually try to prealloc the largest
extent size we can every time we call btrfs_reserve_extent. This can be very
expensive when we are heavily fragmented, burning lots of CPU cycles and loops
through the allocator. So instead notice when we get a smaller chunk from the
allocator than what we specified and use this as the new maximum size we try to
allocate. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Diffstat (limited to '')
| -rw-r--r-- | fs/btrfs/inode.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5ce55f6eefce..a3e078365de5 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9687,6 +9687,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, u64 cur_offset = start; u64 i_size; u64 cur_bytes; + u64 last_alloc = (u64)-1; int ret = 0; bool own_trans = true; @@ -9703,6 +9704,13 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, cur_bytes = min(num_bytes, 256ULL * 1024 * 1024); cur_bytes = max(cur_bytes, min_size); + /* + * If we are severely fragmented we could end up with really + * small allocations, so if the allocator is returning small + * chunks lets make its job easier by only searching for those + * sized chunks. + */ + cur_bytes = min(cur_bytes, last_alloc); ret = btrfs_reserve_extent(root, cur_bytes, min_size, 0, *alloc_hint, &ins, 1, 0); if (ret) { @@ -9711,6 +9719,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, break; } + last_alloc = ins.offset; ret = insert_reserved_file_extent(trans, inode, cur_offset, ins.objectid, ins.offset, ins.offset, |