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#!/usr/bin/env python3
# SPDX-License-Identifier: LGPL-2.1-or-later
import gdb
class sd_dump_hashmaps(gdb.Command):
"dump systemd's hashmaps"
def __init__(self):
super().__init__("sd_dump_hashmaps", gdb.COMMAND_DATA, gdb.COMPLETE_NONE)
def invoke(self, arg, from_tty):
d = gdb.parse_and_eval("hashmap_debug_list")
hashmap_type_info = gdb.parse_and_eval("hashmap_type_info")
uchar_t = gdb.lookup_type("unsigned char")
ulong_t = gdb.lookup_type("unsigned long")
debug_offset = gdb.parse_and_eval("(unsigned long)&((HashmapBase*)0)->debug")
print("type, hash, indirect, entries, max_entries, buckets, creator")
while d:
h = gdb.parse_and_eval(f"(HashmapBase*)((char*){int(d.cast(ulong_t))} - {debug_offset})")
if h["has_indirect"]:
storage_ptr = h["indirect"]["storage"].cast(uchar_t.pointer())
n_entries = h["indirect"]["n_entries"]
n_buckets = h["indirect"]["n_buckets"]
else:
storage_ptr = h["direct"]["storage"].cast(uchar_t.pointer())
n_entries = h["n_direct_entries"]
n_buckets = hashmap_type_info[h["type"]]["n_direct_buckets"]
t = ["plain", "ordered", "set"][int(h["type"])]
print(f'{t}, {h["hash_ops"]}, {bool(h["has_indirect"])}, {n_entries}, {d["max_entries"]}, {n_buckets}, {d["func"].string()}, {d["file"].string()}:{d["line"]}')
if arg != "" and n_entries > 0:
dib_raw_addr = storage_ptr + hashmap_type_info[h["type"]]["entry_size"] * n_buckets
histogram = {}
for i in range(0, n_buckets):
dib = int(dib_raw_addr[i])
histogram[dib] = histogram.get(dib, 0) + 1
for dib in sorted(histogram):
if dib != 255:
print(f"{dib:>3} {histogram[dib]:>8} {float(histogram[dib]/n_entries):.0%} of entries")
else:
print(f"{dib:>3} {histogram[dib]:>8} {float(histogram[dib]/n_buckets):.0%} of slots")
s = sum(dib*count for (dib, count) in histogram.items() if dib != 255) / n_entries
print(f"mean DIB of entries: {s}")
blocks = []
current_len = 1
prev = int(dib_raw_addr[0])
for i in range(1, n_buckets):
dib = int(dib_raw_addr[i])
if (dib == 255) != (prev == 255):
if prev != 255:
blocks += [[i, current_len]]
current_len = 1
else:
current_len += 1
prev = dib
if prev != 255:
blocks += [[i, current_len]]
# a block may be wrapped around
if len(blocks) > 1 and blocks[0][0] == blocks[0][1] and blocks[-1][0] == n_buckets - 1:
blocks[0][1] += blocks[-1][1]
blocks = blocks[0:-1]
print("max block: {}".format(max(blocks, key=lambda a: a[1])))
print("sum block lens: {}".format(sum(b[1] for b in blocks)))
print("mean block len: {}".format(sum(b[1] for b in blocks) / len(blocks)))
d = d["debug_list_next"]
sd_dump_hashmaps()
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