How to Estimate the Kernel Size in Memory

[Tsing]

Hi everyone,


I’m trying to figure out how to measure the memory usage of the kernel at runtime. Specifically, I’d like to know how to get detailed statistics such as:

• total memory used by the kernel
• heap memory
• stack memory
• physical memory
• swapped memory
• mapped memory
• resident memory

Is there a standard way or set of tools to obtain this information? Any pointers or examples would be really helpful.

Thanks in advance!

 

[vmisev]

man vmstat() (pay attention to -m), man kldstat(), sysctl vm.kmem_size, sysctl vm.kmem_map_size

 

[Kai Burghardt]

Hey, welcome to the FreeBSD forums.​

I’m trying to figure out how to measure the memory usage of the kernel at runtime. […]

Have a look at Thread 84787. Apparently you can get some stats(7) via sysctl(8).​

sysctl -d hw.realmem kern.kstack_pages vm.kmem_map_size vm.kmem_size
hw.realmem: Amount of memory (in bytes) reported by the firmware
kern.kstack_pages: Kernel stack size in pages
vm.kmem_map_size: Current kmem allocation size
vm.kmem_size: Size of kernel memory

Programmatically you can use libmemstat(3).​

• swapped memory

Kernel memory is not swapped. It would be detrimental to, yeah, everything.​

• resident memory

Define resident. Once the loader(8) loaded it, the kernel file itself stays resident, duh! There’s probably more.​

Is there a standard way or set of tools to obtain this information?

Nope, it’s all FreeBSD‐specific.​