Python系统资源枚举

Question

I'm trying to get system information. I have to avoid installing third-party packages and libraries or modules that require the latest version of python to run. This is still in early dev and currently only tested on Ubuntu 10.04 but I will play with that later. I'm having trouble with getting the proper information for memory usage.

So far what I have is this:

#! /usr/bin/python

import platform
import multiprocessing
import os

print "\nEnumerating Available System Resources..."

print "\n++++++++++ OS Name and version ++++++++++"

print "Platform:", platform.system()
print "Kernel:", platform.release()
print "Distro:", platform.linux_distribution()
print "Architecture:", platform.architecture()

print "\n++++++++++ CPU Cores ++++++++++"
p = os.popen("ps aux|awk 'NR > 0{s +=$3};END{print s}'").read()
print "Cores:", multiprocessing.cpu_count(), '\nCPU Load:', p

print "\n++++++++++ System Memory ++++++++++\n"

def meminfo():
    meminfo=dict()

    with os.popen('cat /proc/meminfo') as f:
        for line in f:
            meminfo[line.split(':')[0]] = line.split(':')[1].strip()
    return meminfo

if __name__=='__main__':
    meminfo = meminfo()
    print('Total Memory: {0}'.format(meminfo['MemTotal']))
    print('Free Memory: {0}'.format(meminfo['MemFree']))

The problem is that the last portion I get the proper memory stats but I also need to add a "usage" portion in percentage format. I can't figure out how to get the math right, though.

I need this because some of the systems that I work on may be tapped out on ram and I can't allow the script to crash the machine so I will need to also add something in here to evaluate the RAM percentage and CPU percentage and not continue if certain conditions exist such as CPU load over 75% and RAM less than 5% remaining. I would like some insight to those functions, also but the primary concern right now is getting the memory usage percentage. I've been at this for hours and could use some fresh eyes. Thanks!

Answer 1

How about using the free command instead?

import os
import re
def meminfo():

    with os.popen('free -m') as f:
        output = f.read()

    fields = re.search(r'Mem\:\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)',
            output,re.M).group
    return dict(total=fields(1),used=fields(2),free=fields(3),
            shared=fields(4),buffers=fields(5),cached=fields(6))

print meminfo()

Output:

{'used': '3292', 'buffers': '105', 'cached': '2063', 'shared': '0', 'total': '3550', 'free': '257'}

Note that the -m outputs everything in megabytes. You can use -k for kilobytes, -g for gigabytes, or just free by itself to output in bytes.

free should be available pretty much anywhere /proc/meminfo is.

As to your original question, to get the percentage in use you would use:

used/total

or

(total-free)/total

But note that this can be misleading on linux as the used value includes any cached files. So for a really accurate count of memory that is locked so to speak you would use:

(used-cached)/total

or

(total-free-cached)/total