current zfs tuning in RELENG_7 (AMD64) suggestions ?

[Artem Belevich]

>> This information is outdated.  The current max in RELENG_7 for amd64 is
>> ~3.75GB.

Technically, RELENG_7 should allow kmem_size of up to 6G, but the
sysctl variables used for tuning are 32-bit and *that* limits
kmem_size to ~4G.
It's been fixed in -current and can easily be fixed in RELENG_7 (if
it's not fixedyet).

As far as I can tell, all necessary code to support large kmem_size is
already in RELENG_7. It's easy enough to allow even larger kmem_size.
See attached diff that I'm using. With that diff you can set
vm.kmem_size to ~16G.

--Artem
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