tools/gdb-sd_dump_hashmaps.py

   1 #!/usr/bin/env python3
   2 #  -*- Mode: python; coding: utf-8; indent-tabs-mode: nil -*- */
   3 # SPDX-License-Identifier: LGPL-2.1+
   4 #
   5 #  This file is part of systemd.
   6 #
   7 #  Copyright 2014 Michal Schmidt
   8
   9 import gdb
  10
  11 class sd_dump_hashmaps(gdb.Command):
  12         "dump systemd's hashmaps"
  13
  14         def __init__(self):
  15                 super(sd_dump_hashmaps, self).__init__("sd_dump_hashmaps", gdb.COMMAND_DATA, gdb.COMPLETE_NONE)
  16
  17         def invoke(self, arg, from_tty):
  18                 d = gdb.parse_and_eval("hashmap_debug_list")
  19                 all_entry_sizes = gdb.parse_and_eval("all_entry_sizes")
  20                 all_direct_buckets = gdb.parse_and_eval("all_direct_buckets")
  21                 hashmap_base_t = gdb.lookup_type("HashmapBase")
  22                 uchar_t = gdb.lookup_type("unsigned char")
  23                 ulong_t = gdb.lookup_type("unsigned long")
  24                 debug_offset = gdb.parse_and_eval("(unsigned long)&((HashmapBase*)0)->debug")
  25
  26                 print "type, hash, indirect, entries, max_entries, buckets, creator"
  27                 while d:
  28                         h = gdb.parse_and_eval("(HashmapBase*)((char*)%d - %d)" % (int(d.cast(ulong_t)), debug_offset))
  29
  30                         if h["has_indirect"]:
  31                                 storage_ptr = h["indirect"]["storage"].cast(uchar_t.pointer())
  32                                 n_entries = h["indirect"]["n_entries"]
  33                                 n_buckets = h["indirect"]["n_buckets"]
  34                         else:
  35                                 storage_ptr = h["direct"]["storage"].cast(uchar_t.pointer())
  36                                 n_entries = h["n_direct_entries"]
  37                                 n_buckets = all_direct_buckets[int(h["type"])];
  38
  39                         t = ["plain", "ordered", "set"][int(h["type"])]
  40
  41                         print "{}, {}, {}, {}, {}, {}, {} ({}:{})".format(t, h["hash_ops"], bool(h["has_indirect"]), n_entries, d["max_entries"], n_buckets, d["func"], d["file"], d["line"])
  42
  43                         if arg != "" and n_entries > 0:
  44                                 dib_raw_addr = storage_ptr + (all_entry_sizes[h["type"]] * n_buckets)
  45
  46                                 histogram = {}
  47                                 for i in xrange(0, n_buckets):
  48                                         dib = int(dib_raw_addr[i])
  49                                         histogram[dib] = histogram.get(dib, 0) + 1
  50
  51                                 for dib in sorted(iter(histogram)):
  52                                         if dib != 255:
  53                                                 print "{:>3} {:>8} {} of entries".format(dib, histogram[dib], 100.0*histogram[dib]/n_entries)
  54                                         else:
  55                                                 print "{:>3} {:>8} {} of slots".format(dib, histogram[dib], 100.0*histogram[dib]/n_buckets)
  56                                 print "mean DIB of entries: {}".format(sum([dib*histogram[dib] for dib in iter(histogram) if dib != 255])*1.0/n_entries)
  57
  58                                 blocks = []
  59                                 current_len = 1
  60                                 prev = int(dib_raw_addr[0])
  61                                 for i in xrange(1, n_buckets):
  62                                         dib = int(dib_raw_addr[i])
  63                                         if (dib == 255) != (prev == 255):
  64                                                 if prev != 255:
  65                                                         blocks += [[i, current_len]]
  66                                                 current_len = 1
  67                                         else:
  68                                                 current_len += 1
  69
  70                                         prev = dib
  71                                 if prev != 255:
  72                                         blocks += [[i, current_len]]
  73                                 # a block may be wrapped around
  74                                 if len(blocks) > 1 and blocks[0][0] == blocks[0][1] and blocks[-1][0] == n_buckets - 1:
  75                                         blocks[0][1] += blocks[-1][1]
  76                                         blocks = blocks[0:-1]
  77                                 print "max block: {}".format(max(blocks, key=lambda a: a[1]))
  78                                 print "sum block lens: {}".format(sum(b[1] for b in blocks))
  79                                 print "mean block len: {}".format((1.0 * sum(b[1] for b in blocks) / len(blocks)))
  80
  81                         d = d["debug_list_next"]
  82
  83 sd_dump_hashmaps()