[CFR][ZFS] merge Illumos rev. 13346 (set vdev_cache to zero)

[Martin Matuska]

zfs vdev cache (readahead) consumes excessive memory and is very
underutilized.
Set zfs_vdev_cache_size to zero.
This change is present in Solaris 11.

https://www.illumos.org/issues/175
https://www.illumos.org/projects/illumos-gate/repository/revisions/13346

If there are no objections, I will commit this to -HEAD.

-- 
Martin Matuska
FreeBSD committer
http://blog.vx.sk

-------------- next part --------------
A non-text attachment was scrubbed...
Name: 13346.patch
Type: text/x-patch
Size: 1103 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/zfs-devel/attachments/20110620/df47ec5c/13346.bin