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workqueue: Add pwq->stats[] and a monitoring script
Currently, the only way to peer into workqueue operations is through
tracing. While possible, it isn't easy or convenient to monitor
per-workqueue behaviors over time this way. Let's add pwq->stats[] that
track relevant events and a drgn monitoring script -
tools/workqueue/wq_monitor.py.
It's arguable whether this needs to be configurable. However, it currently
only has several counters and the runtime overhead shouldn't be noticeable
given that they're on pwq's which are per-cpu on per-cpu workqueues and
per-numa-node on unbound ones. Let's keep it simple for the time being.
v2: Patch reordered to earlier with fewer fields. Field will be added back
gradually. Help message improved.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,150 @@ | ||
| #!/usr/bin/env drgn | ||
| # | ||
| # Copyright (C) 2023 Tejun Heo <tj@kernel.org> | ||
| # Copyright (C) 2023 Meta Platforms, Inc. and affiliates. | ||
|
|
||
| desc = """ | ||
| This is a drgn script to monitor workqueues. For more info on drgn, visit | ||
| https://github.com/osandov/drgn. | ||
| total Total number of work items executed by the workqueue. | ||
| infl The number of currently in-flight work items. | ||
| CMwake The number of concurrency-management wake-ups while executing a | ||
| work item of the workqueue. | ||
| mayday The number of times the rescuer was requested while waiting for | ||
| new worker creation. | ||
| rescued The number of work items executed by the rescuer. | ||
| """ | ||
|
|
||
| import sys | ||
| import signal | ||
| import os | ||
| import re | ||
| import time | ||
| import json | ||
|
|
||
| import drgn | ||
| from drgn.helpers.linux.list import list_for_each_entry,list_empty | ||
| from drgn.helpers.linux.cpumask import for_each_possible_cpu | ||
|
|
||
| import argparse | ||
| parser = argparse.ArgumentParser(description=desc, | ||
| formatter_class=argparse.RawTextHelpFormatter) | ||
| parser.add_argument('workqueue', metavar='REGEX', nargs='*', | ||
| help='Target workqueue name patterns (all if empty)') | ||
| parser.add_argument('-i', '--interval', metavar='SECS', type=float, default=1, | ||
| help='Monitoring interval (0 to print once and exit)') | ||
| parser.add_argument('-j', '--json', action='store_true', | ||
| help='Output in json') | ||
| args = parser.parse_args() | ||
|
|
||
| def err(s): | ||
| print(s, file=sys.stderr, flush=True) | ||
| sys.exit(1) | ||
|
|
||
| workqueues = prog['workqueues'] | ||
|
|
||
| WQ_UNBOUND = prog['WQ_UNBOUND'] | ||
| WQ_MEM_RECLAIM = prog['WQ_MEM_RECLAIM'] | ||
|
|
||
| PWQ_STAT_STARTED = prog['PWQ_STAT_STARTED'] # work items started execution | ||
| PWQ_STAT_COMPLETED = prog['PWQ_STAT_COMPLETED'] # work items completed execution | ||
| PWQ_STAT_CM_WAKEUP = prog['PWQ_STAT_CM_WAKEUP'] # concurrency-management worker wakeups | ||
| PWQ_STAT_MAYDAY = prog['PWQ_STAT_MAYDAY'] # maydays to rescuer | ||
| PWQ_STAT_RESCUED = prog['PWQ_STAT_RESCUED'] # linked work items executed by rescuer | ||
| PWQ_NR_STATS = prog['PWQ_NR_STATS'] | ||
|
|
||
| class WqStats: | ||
| def __init__(self, wq): | ||
| self.name = wq.name.string_().decode() | ||
| self.unbound = wq.flags & WQ_UNBOUND != 0 | ||
| self.mem_reclaim = wq.flags & WQ_MEM_RECLAIM != 0 | ||
| self.stats = [0] * PWQ_NR_STATS | ||
| for pwq in list_for_each_entry('struct pool_workqueue', wq.pwqs.address_of_(), 'pwqs_node'): | ||
| for i in range(PWQ_NR_STATS): | ||
| self.stats[i] += int(pwq.stats[i]) | ||
|
|
||
| def dict(self, now): | ||
| return { 'timestamp' : now, | ||
| 'name' : self.name, | ||
| 'unbound' : self.unbound, | ||
| 'mem_reclaim' : self.mem_reclaim, | ||
| 'started' : self.stats[PWQ_STAT_STARTED], | ||
| 'completed' : self.stats[PWQ_STAT_COMPLETED], | ||
| 'cm_wakeup' : self.stats[PWQ_STAT_CM_WAKEUP], | ||
| 'mayday' : self.stats[PWQ_STAT_MAYDAY], | ||
| 'rescued' : self.stats[PWQ_STAT_RESCUED], } | ||
|
|
||
| def table_header_str(): | ||
| return f'{"":>24} {"total":>8} {"infl":>5} {"CMwake":>7} {"mayday":>7} {"rescued":>7}' | ||
|
|
||
| def table_row_str(self): | ||
| cm_wakeup = '-' | ||
| mayday = '-' | ||
| rescued = '-' | ||
|
|
||
| if not self.unbound: | ||
| cm_wakeup = str(self.stats[PWQ_STAT_CM_WAKEUP]) | ||
|
|
||
| if self.mem_reclaim: | ||
| mayday = str(self.stats[PWQ_STAT_MAYDAY]) | ||
| rescued = str(self.stats[PWQ_STAT_RESCUED]) | ||
|
|
||
| out = f'{self.name[-24:]:24} ' \ | ||
| f'{self.stats[PWQ_STAT_STARTED]:8} ' \ | ||
| f'{max(self.stats[PWQ_STAT_STARTED] - self.stats[PWQ_STAT_COMPLETED], 0):5} ' \ | ||
| f'{cm_wakeup:>7} ' \ | ||
| f'{mayday:>7} ' \ | ||
| f'{rescued:>7} ' | ||
| return out.rstrip(':') | ||
|
|
||
| exit_req = False | ||
|
|
||
| def sigint_handler(signr, frame): | ||
| global exit_req | ||
| exit_req = True | ||
|
|
||
| def main(): | ||
| # handle args | ||
| table_fmt = not args.json | ||
| interval = args.interval | ||
|
|
||
| re_str = None | ||
| if args.workqueue: | ||
| for r in args.workqueue: | ||
| if re_str is None: | ||
| re_str = r | ||
| else: | ||
| re_str += '|' + r | ||
|
|
||
| filter_re = re.compile(re_str) if re_str else None | ||
|
|
||
| # monitoring loop | ||
| signal.signal(signal.SIGINT, sigint_handler) | ||
|
|
||
| while not exit_req: | ||
| now = time.time() | ||
|
|
||
| if table_fmt: | ||
| print() | ||
| print(WqStats.table_header_str()) | ||
|
|
||
| for wq in list_for_each_entry('struct workqueue_struct', workqueues.address_of_(), 'list'): | ||
| stats = WqStats(wq) | ||
| if filter_re and not filter_re.search(stats.name): | ||
| continue | ||
| if table_fmt: | ||
| print(stats.table_row_str()) | ||
| else: | ||
| print(stats.dict(now)) | ||
|
|
||
| if interval == 0: | ||
| break | ||
| time.sleep(interval) | ||
|
|
||
| if __name__ == "__main__": | ||
| main() |