The mysterious kern.maxswzone

Andrea Venturoli ml at
Mon Jan 21 17:32:07 UTC 2019

On 1/21/19 5:03 PM, RW via freebsd-questions wrote:

> Do you know, for sure, that there isn't a risk of a panic if you run out
> of zone space before you run out of swap.

Short answer: NO!
I don't know for sure, but I think this isn't the case.
 From what I read around, IIUC, zone space is used to manage swap space, 
so the only effect is that some swap space won't be used.
I hope someone with more solid knowledge steps up...

> In amd64 you can't
> increase the zone size because that computed default is also the limit.

Then, why do I get the same warning ("warning: increase kern.maxswzone 
or reduce amount of swap") if the suggested operation is not possible?
I guess the message should be patched.

> The value is in bytes, so it isn't huge. Try setting it to a few percent
> above
>    36175872 * 131072 / 113792
> something like 42500000

"Huge" compared to what? :)
The OP has 512MiB of RAM: 42500000 byte is not a negligible amount in 
that case, but he is the only one who knows if it's worth, based on his 


More information about the freebsd-questions mailing list