こんなのでいいんだろうか?
% sysctl -a | grep vm.stats.vm | grep count
vm.stats.vm.v_page_count: 62119
vm.stats.vm.v_free_count: 50385
vm.stats.vm.v_wire_count: 4987
vm.stats.vm.v_active_count: 3714
vm.stats.vm.v_inactive_count: 2914
vm.stats.vm.v_cache_count: 2
% sysctl vm.stats.vm.v_page_size
vm.stats.vm.v_page_size: 4096
% echo "4096*`sysctl vm.stats.vm.v_free_count | cut -d' ' -f2`/1024/1024" | bc
197
% top -n
last pid: 1607; load averages: 0.00, 0.00, 0.00 up 0+04:47:44 00:13:45
39 processes: 1 running, 38 sleeping
Mem: 14M Active, 11M Inact, 20M Wired, 8K Cache, 16M Buf, 197M Free
Swap: 487M Total, 487M Free
% swapinfo -h
Device 1K-blocks Used Avail Capacity
/dev/ad0s1b 498504 0B 487M 0%