1.2.1 loader.conf sets vm.kmem_size larger than memory?

[ktims]

Wondering on the rationale for this. It's currently being set larger than the total memory on my ALIX box and I'm concerned that something stupid is going to happen when/if the allocator ever tries to use this extra memory. I'm not a FreeBSD expert and I can't find any documentation on this tunable, but it seems strange to set it to 400+MB on boot when the default the kernel selects on this machine is about 80MB, and it seems to be able to scale it on its own. Probably harmless but it seems weird.

Comments?

[wallabybob]

@ktims:

Wondering on the rationale for this. It's currently being set larger than the total memory on my ALIX box and I'm concerned that something stupid is going to happen when/if the allocator ever tries to use this extra memory.

There is no point setting vm.kmem_size larger than physical memory size. You probably don't want the kernel growing to use all of physical memory and leaving nothing for applications.

On my pfSense box which has had multiple upgrades through the 1.2.1 series and is now running the released 1.2.1 /boot/loader.conf contains

autoboot_delay="1"
kern.ipc.nmbclusters="0"

I don't remember making any changes to this file. I wonder how your /boot/loader.conf got an entry for vm.kmem_size. I suspect you could safely delete it. I wonder if there is any other "junk" in there.