gistfile1.py

#!/usr/bin/env python                                                            
import struct                                                                    
from collections import defaultdict                                              
                                                                                 
# mysql -Ne "select si.space, CONCAT(st.SCHEMA,'.', st.NAME, '/', si.name) from INNODB_SYS_INDEXES si, INNODB_SYS_TABLES st where st.TABLE_ID=si.TABLE_ID" information_schema > map
def read_map(map_file = './map'):                                                
    with open(map_file, 'r') as fd:                                              
        return  dict((int(k), v) for k, v in [line.strip().split() for line in fd.readlines()])
                                                                                 
def read_lru(lru_file = './ib_lru_dump'):                                        
    entries = defaultdict(lambda: 1)                                             
    total = 0                                                                    
    with open(lru_file, 'rb') as fd:                                             
        while True:                                                              
            i = fd.read(8)                                                       
            if i == "": break                                                    
            space_id, page_no = struct.unpack('>II', i)                          
            if space_id > 0 or page_no > 0:                                      
                entries[space_id] += 1                                           
    return entries                                                               
                                                                                 
                                                                                 
def to_gb(pages):                                                                
    return pages*16/1024/1024                                                    
                                                                                 
lookup = read_map()                                                              
data = read_lru()                                                                
total = sum(data.values())                                                       
for k, v in sorted(data.iteritems(), key = lambda(k, v): v):                     
    if k in lookup:                                                              
        print "%s %dGB (%f%%)" % (lookup[k], to_gb(v), float(v)/total*100)       
    else:                                                                        
        print "UNKNOWN%d: %d" % (k, v)                                           
                                                                                 
print "%d pages (%d GB) accounted for" % (total, to_gb(total))                   

http://docs.python.org/2/library/struct.html

ya, I just copied the mysql source. First attempt was wrong anyway, this works (thanks to http://www.mysqlperformanceblog.com/2010/01/20/xtradb-feature-save-restore-buffer-pool/)