tools/workqueue/wq_monitor.py

   1 #!/usr/bin/env drgn
   2 #
   3 # Copyright (C) 2023 Tejun Heo <tj@kernel.org>
   4 # Copyright (C) 2023 Meta Platforms, Inc. and affiliates.
   5
   6 desc = """
   7 This is a drgn script to monitor workqueues. For more info on drgn, visit
   8 https://github.com/osandov/drgn.
   9
  10   total    Total number of work items executed by the workqueue.
  11
  12   infl     The number of currently in-flight work items.
  13
  14   CPUtime  Total CPU time consumed by the workqueue in seconds. This is
  15            sampled from scheduler ticks and only provides ballpark
  16            measurement. "nohz_full=" CPUs are excluded from measurement.
  17
  18   CPUitsv  The number of times a concurrency-managed work item hogged CPU
  19            longer than the threshold (workqueue.cpu_intensive_thresh_us)
  20            and got excluded from concurrency management to avoid stalling
  21            other work items.
  22
  23   CMwake   The number of concurrency-management wake-ups while executing a
  24            work item of the workqueue.
  25
  26   mayday   The number of times the rescuer was requested while waiting for
  27            new worker creation.
  28
  29   rescued  The number of work items executed by the rescuer.
  30 """
  31
  32 import sys
  33 import signal
  34 import os
  35 import re
  36 import time
  37 import json
  38
  39 import drgn
  40 from drgn.helpers.linux.list import list_for_each_entry,list_empty
  41 from drgn.helpers.linux.cpumask import for_each_possible_cpu
  42
  43 import argparse
  44 parser = argparse.ArgumentParser(description=desc,
  45                                  formatter_class=argparse.RawTextHelpFormatter)
  46 parser.add_argument('workqueue', metavar='REGEX', nargs='*',
  47                     help='Target workqueue name patterns (all if empty)')
  48 parser.add_argument('-i', '--interval', metavar='SECS', type=float, default=1,
  49                     help='Monitoring interval (0 to print once and exit)')
  50 parser.add_argument('-j', '--json', action='store_true',
  51                     help='Output in json')
  52 args = parser.parse_args()
  53
  54 def err(s):
  55     print(s, file=sys.stderr, flush=True)
  56     sys.exit(1)
  57
  58 workqueues              = prog['workqueues']
  59
  60 WQ_UNBOUND              = prog['WQ_UNBOUND']
  61 WQ_MEM_RECLAIM          = prog['WQ_MEM_RECLAIM']
  62
  63 PWQ_STAT_STARTED        = prog['PWQ_STAT_STARTED']      # work items started execution
  64 PWQ_STAT_COMPLETED      = prog['PWQ_STAT_COMPLETED']    # work items completed execution
  65 PWQ_STAT_CPU_TIME       = prog['PWQ_STAT_CPU_TIME']     # total CPU time consumed
  66 PWQ_STAT_CPU_INTENSIVE  = prog['PWQ_STAT_CPU_INTENSIVE'] # wq_cpu_intensive_thresh_us violations
  67 PWQ_STAT_CM_WAKEUP      = prog['PWQ_STAT_CM_WAKEUP']    # concurrency-management worker wakeups
  68 PWQ_STAT_MAYDAY         = prog['PWQ_STAT_MAYDAY']       # maydays to rescuer
  69 PWQ_STAT_RESCUED        = prog['PWQ_STAT_RESCUED']      # linked work items executed by rescuer
  70 PWQ_NR_STATS            = prog['PWQ_NR_STATS']
  71
  72 class WqStats:
  73     def __init__(self, wq):
  74         self.name = wq.name.string_().decode()
  75         self.unbound = wq.flags & WQ_UNBOUND != 0
  76         self.mem_reclaim = wq.flags & WQ_MEM_RECLAIM != 0
  77         self.stats = [0] * PWQ_NR_STATS
  78         for pwq in list_for_each_entry('struct pool_workqueue', wq.pwqs.address_of_(), 'pwqs_node'):
  79             for i in range(PWQ_NR_STATS):
  80                 self.stats[i] += int(pwq.stats[i])
  81
  82     def dict(self, now):
  83         return { 'timestamp'            : now,
  84                  'name'                 : self.name,
  85                  'unbound'              : self.unbound,
  86                  'mem_reclaim'          : self.mem_reclaim,
  87                  'started'              : self.stats[PWQ_STAT_STARTED],
  88                  'completed'            : self.stats[PWQ_STAT_COMPLETED],
  89                  'cpu_time'             : self.stats[PWQ_STAT_CPU_TIME],
  90                  'cpu_intensive'        : self.stats[PWQ_STAT_CPU_INTENSIVE],
  91                  'cm_wakeup'            : self.stats[PWQ_STAT_CM_WAKEUP],
  92                  'mayday'               : self.stats[PWQ_STAT_MAYDAY],
  93                  'rescued'              : self.stats[PWQ_STAT_RESCUED], }
  94
  95     def table_header_str():
  96         return f'{"":>24} {"total":>8} {"infl":>5} {"CPUtime":>8} '\
  97             f'{"CPUitsv":>7} {"CMwake":>7} {"mayday":>7} {"rescued":>7}'
  98
  99     def table_row_str(self):
 100         cpu_intensive = '-'
 101         cm_wakeup = '-'
 102         mayday = '-'
 103         rescued = '-'
 104
 105         if not self.unbound:
 106             cpu_intensive = str(self.stats[PWQ_STAT_CPU_INTENSIVE])
 107             cm_wakeup = str(self.stats[PWQ_STAT_CM_WAKEUP])
 108
 109         if self.mem_reclaim:
 110             mayday = str(self.stats[PWQ_STAT_MAYDAY])
 111             rescued = str(self.stats[PWQ_STAT_RESCUED])
 112
 113         out = f'{self.name[-24:]:24} ' \
 114               f'{self.stats[PWQ_STAT_STARTED]:8} ' \
 115               f'{max(self.stats[PWQ_STAT_STARTED] - self.stats[PWQ_STAT_COMPLETED], 0):5} ' \
 116               f'{self.stats[PWQ_STAT_CPU_TIME] / 1000000:8.1f} ' \
 117               f'{cpu_intensive:>7} ' \
 118               f'{cm_wakeup:>7} ' \
 119               f'{mayday:>7} ' \
 120               f'{rescued:>7} '
 121         return out.rstrip(':')
 122
 123 exit_req = False
 124
 125 def sigint_handler(signr, frame):
 126     global exit_req
 127     exit_req = True
 128
 129 def main():
 130     # handle args
 131     table_fmt = not args.json
 132     interval = args.interval
 133
 134     re_str = None
 135     if args.workqueue:
 136         for r in args.workqueue:
 137             if re_str is None:
 138                 re_str = r
 139             else:
 140                 re_str += '|' + r
 141
 142     filter_re = re.compile(re_str) if re_str else None
 143
 144     # monitoring loop
 145     signal.signal(signal.SIGINT, sigint_handler)
 146
 147     while not exit_req:
 148         now = time.time()
 149
 150         if table_fmt:
 151             print()
 152             print(WqStats.table_header_str())
 153
 154         for wq in list_for_each_entry('struct workqueue_struct', workqueues.address_of_(), 'list'):
 155             stats = WqStats(wq)
 156             if filter_re and not filter_re.search(stats.name):
 157                 continue
 158             if table_fmt:
 159                 print(stats.table_row_str())
 160             else:
 161                 print(stats.dict(now))
 162
 163         if interval == 0:
 164             break
 165         time.sleep(interval)
 166
 167 if __name__ == "__main__":
 168     main()