Can FreeBSD benefit from MacOS X ZFS?

[Robert Watson]

On Thu, 17 Jan 2008, Dag-Erling Smørgrav wrote:

> Wes Morgan <morganw at chemikals.org> writes:
>
>> As the subject says... Can FreeBSD benefit from the macos port of zfs? I 
>> know this is a VERY new announcement, but not knowing much about macos x in 
>> general I'm wondering how much it might help our tree, with respect to both 
>> the memory and 32-bit issues. Just throwing it out there for discussion, if 
>> anyone has any knowledge of both.
>
> Did you miss the part where Apple no longer sell 32-bit computers?

Actually, the first generation MacBook/MacBook Pro's donly have 64-bit 
support, and both the kernel and user address spaces are 32-bit on those 
systems.  They did, however, have PAE to support larger physical memories. 
More recent Intel Macs have 64-bit address support for userspace but 32-bit 
kernels.  Unlike with FreeBSD, the Mac OS X kernel runs in its own dedicated 
32-bit address space rather than splitting a single 32-bit address space with 
userspace.  This leads to greater system call overhead (system calls require a 
full context switch) but much more kernel address space.  My impression has 
been that Apple has also had challenges dealing with ZFS's run-away resource 
use, however...

Robert N M Watson
Computer Laboratory
University of Cambridge