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NTFS-3G has been installed, and was built with UBLIO support.

The UBLIO layer is configured through environment variables, which are read
when mounting the filesystem. The following are available:

NTFS_USE_UBLIO	- Enable the UBLIO cache.
UBLIO_BLOCKSIZE	- Actual reads/writes will be multiples of this quantity.
UBLIO_ITEMS	- Number of cache entries, each of UBLIO_BLOCKSIZE length.
UBLIO_GRACE	- Number of times a cache entry will refuse being recycled.
UBLIO_SYNC_IO	- If enabled, all writes will be immediatly executed.

To give an idea about tuning, here are the default values with some notes
(they are only based on some simple benchmarks, and may be wrong):

NTFS_USE_UBLIO	- 1. Disabling it drastically decreases performance.
UBLIO_BLOCKSIZE	- 262144 (256KB). Larger improves reading/writing speed of
		  large files, and smaller makes filesystem operations
		  (creation, deletion, moving, find(1)) perform faster.
		  Try 2/4MB and 512/256KB for the different approaches. Note
		  that after that points performance descreases again.
UBLIO_ITEMS	- 64. Higher increases speed of filesystem operations. Try 128.
UBLIO_GRACE	- 32. Makes the cache items have more chances to be reused.
UBLIO_SYNC_IO	- 0. If enabled, highly decreases writing speed, but the data
		  is immediatly written to the disk.

For example (improves performance over large files, but read below):

# env UBLIO_BLOCKSIZE=2097152 ntfs-3g /dev/ad0s1 /mnt

Alternatively these variables could be set in the shell startup file. For
example if you are using it in /etc/fstab add them to /etc/profile. In that
case, use "ntfs-3g" as the type and add the "late" parameter. Note that this
requires fusefs_enable="YES" to be present in /etc/rc.conf.

It is also possible to enforce block aligned I/O on regular files by setting
the FORCE_ALIGNED_IO variable (it will be set to 512 bytes), but this is only
useful for testing purposes and in practice has no use.

Note that higher values for UBLIO_BLOCKSIZE and UBLIO_ITEMS increase the
memory usage by their product in bytes. For example, if you set it to 1MB it
would consume 64MB. To decrease it to 16MB you could set UBLIO_BLOCKSIZE to
256KB (currently this is the default). Small values like 4096 can be used and
also perform fine.

When doing many simultaneous file operations on FUSE and native (not FUSE)
filesystems sometimes one of them fails: read(2) returns -1 and sets errno to
EAGAIN. The greater UBLIO_BLOCKSIZE is, more chances this has to happen (this
still has to be clarified).

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