Re: Time to bump default VM_SWZONE_SIZE_MAX?

On Sun, Aug 12, 2012 at 5:44 PM, Colin Percival <cperciva_at_freebsd.org>wrote:

> Hi all,
>
> If I'm understanding things correctly, the "maxswzone" value -- set by the
> kern.maxswzone loader tunable or to VM_SWZONE_SIZE_MAX by default -- should
> be approximately 9 MiB per GiB of swap space.
>
> The current default for VM_SWZONE_SIZE_MAX was set in August 2002 to 32
> MiB;
> meaning that anyone who wants to use more than ~ 3.5 GB of swap space ought
> to set kern.maxswzone in /boot/loader.conf.
>
> Is it time to increase this default on amd64?  (I understand that keeping
> the
> value low on i386 is important due to KVA limitations, but amd64 has far
> more
> address space available...)
>
>
The short answer is "Yes."  The long answer is that amd64, ia64, etc.
shouldn't have this limit at all.  The swap zone objects are small objects
that could be allocated by uma_small_alloc() and accessed through the
direct map.

Alan