[CFT] ZFS v16 with stat() speedup

As I have imported some more improvements to the ZFS v15 patch that also
target speed,
I am now calling for testing of v16 with mainly the following important
(post-v16) enhancement (and some related bugfixes):

OpenSolaris Bug ID: 6775100 stat() performance on files on zfs should be
improved
This significantly improves stat() performance of ZFS and has a very
positive effect on e.g webservers using PHP
(I benchmarked a ~20% speed increase of PHP webserving)

The patch is available here:
http://people.freebsd.org/~mm/patches/zfs/v16/head-v16-extended.patch

List of all changes (compared to current head and v15-patch):
http://people.freebsd.org/~mm/patches/zfs/v16/head-v16.txt

And again some ISOs (patched 8.1rc1) for testing:
http://mfsbsd.vx.sk/iso/8.1rc1-zfsv16.iso (without symbols, 98.7MB)
http://mfsbsd.vx.sk/iso/8.1rc1-zfsv16-debug.iso (with kernel symbols,
187.6MB)

Login/password: root/mfsroot

You can test these ISO's in Virtualbox, other emulation software or
real-world systems.
They contain a full installable distribution, here is a zfsinstall
command example on an ad4 disk, with ZFS version 16, 4GB extra swap
partition, lzjb compression and fletcher4 checksum:

1. Login as root (root:mfsroot)
2. mount_cd9660 /dev/acd0 /cdrom
3. zfsinstall -V 16 -t /cdrom/8.1-RC1-amd64.tar.xz -s 4G -c -4 -d ad4

When mfsbsd (not the installed system) is booted, there is a python and
py-zfs package in /packages. You can copy and install these to your
installed system for full pyzfs functionality (zfs userspace, zfs
groupspace, zfs allow, zfs unallow).

Thanks for testing,
mm