memory-usage.py

#!/usr/bin/python

import subprocess
import re

# Get process info
ps = subprocess.Popen(['ps', '-caxm', '-orss,comm'], stdout=subprocess.PIPE).communicate()[0].decode()
vm = subprocess.Popen(['vm_stat'], stdout=subprocess.PIPE).communicate()[0].decode()

# Iterate processes
processLines = ps.split('\n')
sep = re.compile('[\s]+')
rssTotal = 0 # kB
for row in range(1,len(processLines)):
    rowText = processLines[row].strip()
    rowElements = sep.split(rowText)
    try:
        rss = float(rowElements[0]) * 1024
    except:
        rss = 0 # ignore...
    rssTotal += rss

# Process vm_stat
vmLines = vm.split('\n')
sep = re.compile(':[\s]+')
vmStats = {}
for row in range(1,len(vmLines)-2):
    rowText = vmLines[row].strip()
    rowElements = sep.split(rowText)
    vmStats[(rowElements[0])] = int(rowElements[1].strip('\.')) * 4096

print 'Wired Memory:\t\t%d MB' % ( vmStats["Pages wired down"]/1024/1024 )
print('Active Memory:\t\t%d MB' % ( vmStats["Pages active"]/1024/1024 ))
print('Inactive Memory:\t%d MB' % ( vmStats["Pages inactive"]/1024/1024 ))
print('Free Memory:\t\t%d MB' % ( vmStats["Pages free"]/1024/1024 ))
print('Real Mem Total (ps):\t%.3f MB' % ( rssTotal/1024/1024 ))

example from my system right now:

[troy@MacBook-Pro Documents]$ python mem.py 
Wired Memory:		2775 MB
Active Memory:		5958 MB
Inactive Memory:	5078 MB
Free Memory:		410 MB
Real Mem Total (ps):	11756.645 MB

https://apple.stackexchange.com/questions/67031/isnt-inactive-memory-a-waste-of-resources

Per this, it seems Free+Inactive for me is 5,488MB out of 16GB - so it's about 1/3rd like the article says is a healthy amount.

In Windows they report this very differently - or maybe use memory differently - my current system in windows shows as:

Total Physical Memory:     32,438 MB
Available Physical Memory: 27,786 MB

So just using these 2 things, windows is using 15% of it's memory, but it's probably safe to assume mac is always trying to use 66%+ for efficiency.

So for v1 lets go with this;

totalmem = 16,000
avail = 5488
---- 5488/16000=0.343 (34% free, 66% used)
usedpercent = 66

So we're going to make a formula to soften this a bit and be a little closer to "windows reality" so that we can use the same counters for both platforms.

109.8591 - (input * 2.453182) + (0.02409091 * input * input)

where input is the "usedpercent"

[79] pry(main)> input = 66
=> 66
[80] pry(main)> 109.8591 - (input * 2.453182) + (0.02409091 * input * input)
=> 52.88909196
[81] pry(main)> input = 90
=> 90
[82] pry(main)> 109.8591 - (input * 2.453182) + (0.02409091 * input * input)
=> 84.20909099999999
[83] pry(main)> input = 99
^[[A=> 99
[84] pry(main)> 109.8591 - (input * 2.453182) + (0.02409091 * input * input)
=> 103.10909090999999

We can add a min 1 and max 100 if that helps