The mysterious kern.maxswzone

Victor Sudakov vas at
Wed Jan 16 02:20:49 UTC 2019

Dear Colleagues,

I have a small 11.2-RELEASE-p8 i386 system with 512M swap and 256M RAM:

# swapinfo
Device          1K-blocks     Used    Avail Capacity
/dev/mirror/gm0s1b    524288    29656   494632     6%

I guess it's not an extraordinary amount of swap for this amount of RAM.

However, on boot I see the warning:

warning: total configured swap (131072 pages) exceeds maximum recommended amount (113792 pages).
warning: increase kern.maxswzone or reduce amount of swap.

# sysctl kern.maxswzone
kern.maxswzone: 36175872

I have some questions:

1. Where is this kern.maxswzone tunable documented?

2. In what units is it measured? What is 36175872, are these bytes?

3. How do I calculate kern.maxswzone to suit my amount of RAM and swap?

36175872/113792=317.91 which confuses me even more (division with

Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
2:5005/49 at fidonet
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