Quick script to find out how much RAM is being used inefficiently or wasted.

wastedpages.py

#!/bin/env python3

# Requires https://github.com/Hello1024/devmem-full-access
# Requires pip install 
from bloom_filter import BloomFilter  # 
import re
import hashlib 

def allRamPages():
    with open('/proc/iomem', 'r') as iomemfile:
        for iomemline in iomemfile:
            # iomemline looks like "ca30c000-cd820fff : System RAM"
            x = re.search(r"^([0-9a-f]*)-([0-9a-f]*) : System RAM$", iomemline)

            if not x: continue

            low = int(x.group(1), 16)
            high = int(x.group(2), 16)

            low = low
            while low < high:
                yield low
                low = low + 4096

devmem = open('/dev/mem', 'rb')
bloom = BloomFilter(max_elements=2**34/2**12, error_rate=0.001)

same = 0
notsame = 0
fail = 0
zerocount=0

zerohash = hashlib.md5(b'\x00'*4096).digest()

for pagenum in allRamPages():
    try:
        devmem.seek(pagenum)
        data = devmem.read(4096)
        data = hashlib.md5(data).digest()

        if (data==zerohash):
            zerocount=zerocount+1
            continue

        if data in bloom:
            same = same+1
            continue

        notsame = notsame+1
        bloom.add(data)
    except PermissionError:
        fail = fail+1

    if (pagenum%(1024*4096)==0): print(f'{pagenum:02X} done.  {zerocount} zero, {same} same, {notsame} not the same, {fail} failed.')