API to compute total RAM memory wired-down by all processes?

Question

Hi. We have a time-critical application that wires-down large memory blocks with mlock() and munlock(). We are concerned that, if other applications are running that are also wiring-down memory, we may inadvertently wire-down all the RAM in the computer, and the computer will hang (this has happened a couple of times).
The solution we would like to adopt is: we compute the total memory wired-down on the computer, by all processes, so we can know whether or not we can wire-down. In other words, we want to, in software, compute the same figure that the Activity Monitor shows in its memory-usage pie chart.
Question: Can anyone point us at an API to compute the total of all wired down memory, from all processes? Thanks in advance.

Answer 1

Thanks for the ideas. What I learned after pursuing the above suggestions, is:
1) sysctl() does not return the amount of Wired-down memory, or if it does, it is just one process
2) "top" shell command does output the Wired-down memory count of all processes. The "top" value is identical to the Activity Monitor value. Unfortunately, there is no API for "top".
3) There is a lower-level mach function host_statistics() (analagous to sysctl?) which will return VM stats: use HOSTVMINFO type (outputs structure vmstatistics_datat) which does include wired-down memory. However, the output value for wired-down memory is not the total of all processes (it is significantly smaller than the wired-down figure from "top" or Activity Monitor). Strangely, the "total active" and "total inactive" values from host_statistics() do reflect all processes. The mystery is: why does host_statistics() under-report the wired value (e.g. it says 400 MB when "top" shows 700 MB).
In summary: host_statistics() is tantalizingly close to what I need, but does not output the correct value. "top" is more accurate, but slow and there is no API.