Re: [PATCH] a character device counting kernel pages

[Matt Thomas <matt%3am-software.com@localhost>]

On Aug 14, 2008, at 7:00 AM, Ilya Dogolazky wrote:

The concept is good, but the use of mdpage is machine-dependent and  
PVF_KMPAGE
is arm-specific.  Walking all the pages to keep the count is not  
correct.
Instead, I've added a sysctl node to pmap.c (machdep.kmpages) which will
return the number of pages with PMAP_KMPAGE set.

> the attached patch is implementing a simple counter of memory pages  
> used by
> the kernel.
>
> This kernel memory consumption measuring device (/dev/kp0,  
> major=239, minor=0)
> is reporting (in decimal form, useful for shell scripts) the number of
> physical memory pages used by the kernel itself. It is tested for  
> ARM only,
> but will probably work with some other architectures too. To enable  
> it add the
> line "pseudo-device pagecounter" to the config file and create the  
> device node
> (mknod /dev/kp0 c 239 0).
>
> Usage in a shell script: KERNEL_MEM=$(cat /dev/kp0)
>
> Any comment and suggestions are welcome.

Now you can do sysctl -n machdep.kmpages