There two things to note here:

1. The vast majority of the memory is being used by the ZFS cache, but
   appears under 'kernel heap'.  If you actually need the memory, it
   _should_ be released.   Under UFS, this cache appears as the 'page
   cache', and users understand that it can be released when needed.
   The same is true of ZFS, but it's just not accounted for as separate
   memory.  Now, the VM hooks needed to do this are somewhat add hoc at
   the moment, but the ZFS cache should keep itself from consuming 100%
   of the available memory.

2. There is a difference between VA (virtual addressing) and physical
   memory.  See the following thread for a more complete discussion:

   http://www.opensolaris.org/jive/thread.jspa?threadID=10774&tstart=45&start=15

So the (apparent) high kernel memory consumption is expected, and does
not indicate any type of problem.  Applications actually receiving
ENOMEM should not happen, and may indicate that there are some
circumstances where the VM interfaces are currently inadequate.  Someone
else on the ZFS team may be able to get some more specifics from you to
figure out what's really going on.

- Eric

On Thu, Jul 20, 2006 at 04:03:50PM -0700, Joseph Mocker wrote:
> 
> >
> >>So what's going on! Please help. I want my memory back!
> >
> >
> >This is essentially by design, due to the way that ZFS uses kernel
> >memory for caching and other stuff.
> >
> >You can alleviate this somewhat by running a 64bit processor, which
> >has a significantly larger address space to play with.
> 
> Uhh. If I don't have any more physical memory, how does a 64bit 
> processor help?
> 
> FWIW, this is on a SunBlade 2000 running in 64bit mode:
> 
> [EMAIL PROTECTED]: uname -a
> SunOS watt 5.10 Generic_118833-17 sun4u sparc SUNW,Sun-Blade-1000
> [EMAIL PROTECTED]: isainfo
> sparcv9 sparc
> 
> _______________________________________________
> zfs-discuss mailing list
> [email protected]
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

--
Eric Schrock, Solaris Kernel Development       http://blogs.sun.com/eschrock
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