tools/gdb-sd_dump_hashmaps.py

   1 #!/usr/bin/env python3
   2 #  -*- Mode: python; coding: utf-8; indent-tabs-mode: nil -*- */
   3 #
   4 #  This file is part of systemd.
   5 #
   6 #  Copyright 2014 Michal Schmidt
   7 #
   8 #  systemd is free software; you can redistribute it and/or modify it
   9 #  under the terms of the GNU Lesser General Public License as published by
  10 #  the Free Software Foundation; either version 2.1 of the License, or
  11 #  (at your option) any later version.
  12 #
  13 #  systemd is distributed in the hope that it will be useful, but
  14 #  WITHOUT ANY WARRANTY; without even the implied warranty of
  15 #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16 #  Lesser General Public License for more details.
  17 #
  18 #  You should have received a copy of the GNU Lesser General Public License
  19 #  along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20
  21 import gdb
  22
  23 class sd_dump_hashmaps(gdb.Command):
  24         "dump systemd's hashmaps"
  25
  26         def __init__(self):
  27                 super(sd_dump_hashmaps, self).__init__("sd_dump_hashmaps", gdb.COMMAND_DATA, gdb.COMPLETE_NONE)
  28
  29         def invoke(self, arg, from_tty):
  30                 d = gdb.parse_and_eval("hashmap_debug_list")
  31                 all_entry_sizes = gdb.parse_and_eval("all_entry_sizes")
  32                 all_direct_buckets = gdb.parse_and_eval("all_direct_buckets")
  33                 hashmap_base_t = gdb.lookup_type("HashmapBase")
  34                 uchar_t = gdb.lookup_type("unsigned char")
  35                 ulong_t = gdb.lookup_type("unsigned long")
  36                 debug_offset = gdb.parse_and_eval("(unsigned long)&((HashmapBase*)0)->debug")
  37
  38                 print "type, hash, indirect, entries, max_entries, buckets, creator"
  39                 while d:
  40                         h = gdb.parse_and_eval("(HashmapBase*)((char*)%d - %d)" % (int(d.cast(ulong_t)), debug_offset))
  41
  42                         if h["has_indirect"]:
  43                                 storage_ptr = h["indirect"]["storage"].cast(uchar_t.pointer())
  44                                 n_entries = h["indirect"]["n_entries"]
  45                                 n_buckets = h["indirect"]["n_buckets"]
  46                         else:
  47                                 storage_ptr = h["direct"]["storage"].cast(uchar_t.pointer())
  48                                 n_entries = h["n_direct_entries"]
  49                                 n_buckets = all_direct_buckets[int(h["type"])];
  50
  51                         t = ["plain", "ordered", "set"][int(h["type"])]
  52
  53                         print "%s, %s, %s, %d, %d, %d, %s (%s:%d)" % (t, h["hash_ops"], bool(h["has_indirect"]), n_entries, d["max_entries"], n_buckets, d["func"], d["file"], d["line"])
  54
  55                         if arg != "" and n_entries > 0:
  56                                 dib_raw_addr = storage_ptr + (all_entry_sizes[h["type"]] * n_buckets)
  57
  58                                 histogram = {}
  59                                 for i in xrange(0, n_buckets):
  60                                         dib = int(dib_raw_addr[i])
  61                                         histogram[dib] = histogram.get(dib, 0) + 1
  62
  63                                 for dib in sorted(iter(histogram)):
  64                                         if dib != 255:
  65                                                 print "%3d %8d %f%% of entries" % (dib, histogram[dib], 100.0*histogram[dib]/n_entries)
  66                                         else:
  67                                                 print "%3d %8d %f%% of slots" % (dib, histogram[dib], 100.0*histogram[dib]/n_buckets)
  68                                 print "mean DIB of entries: %f" % (sum([dib*histogram[dib] for dib in iter(histogram) if dib != 255])*1.0/n_entries)
  69
  70                                 blocks = []
  71                                 current_len = 1
  72                                 prev = int(dib_raw_addr[0])
  73                                 for i in xrange(1, n_buckets):
  74                                         dib = int(dib_raw_addr[i])
  75                                         if (dib == 255) != (prev == 255):
  76                                                 if prev != 255:
  77                                                         blocks += [[i, current_len]]
  78                                                 current_len = 1
  79                                         else:
  80                                                 current_len += 1
  81
  82                                         prev = dib
  83                                 if prev != 255:
  84                                         blocks += [[i, current_len]]
  85                                 # a block may be wrapped around
  86                                 if len(blocks) > 1 and blocks[0][0] == blocks[0][1] and blocks[-1][0] == n_buckets - 1:
  87                                         blocks[0][1] += blocks[-1][1]
  88                                         blocks = blocks[0:-1]
  89                                 print "max block: %s" % max(blocks, key=lambda a: a[1])
  90                                 print "sum block lens: %d" % sum(b[1] for b in blocks)
  91                                 print "mean block len: %f" % (1.0 * sum(b[1] for b in blocks) / len(blocks))
  92
  93                         d = d["debug_list_next"]
  94
  95 sd_dump_hashmaps()