[PATCH v2 4/6] writeback: add wb_monitor.py script to monitor writeback info on bdi
From: Kemeng Shi
Date: Wed Mar 27 2024 - 03:03:23 EST
Add wb_monitor.py script to monitor writeback information on backing dev
which makes it easier and more convenient to observe writeback behaviors
of running system.
The wb_monitor.py script is written based on wq_monitor.py.
Following domain hierarchy is tested:
global domain (320G)
/ \
cgroup domain1(10G) cgroup domain2(10G)
| |
bdi wb1 wb2
The wb_monitor.py script output is as following:
/wb_monitor.py 252:16 -c
writeback reclaimable dirtied written avg_bw
252:16_1 0 0 0 0 102400
252:16_4284 672 820064 9230368 8410304 685612
252:16_4325 896 819840 10491264 9671648 652348
252:16 1568 1639904 19721632 18081952 1440360
writeback reclaimable dirtied written avg_bw
252:16_1 0 0 0 0 102400
252:16_4284 672 820064 9230368 8410304 685612
252:16_4325 896 819840 10491264 9671648 652348
252:16 1568 1639904 19721632 18081952 1440360
..
Signed-off-by: Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
Suggested-by: Tejun Heo <tj@xxxxxxxxxx>
---
tools/writeback/wb_monitor.py | 172 ++++++++++++++++++++++++++++++++++
1 file changed, 172 insertions(+)
create mode 100644 tools/writeback/wb_monitor.py
diff --git a/tools/writeback/wb_monitor.py b/tools/writeback/wb_monitor.py
new file mode 100644
index 000000000000..5e3591f1f9a9
--- /dev/null
+++ b/tools/writeback/wb_monitor.py
@@ -0,0 +1,172 @@
+#!/usr/bin/env drgn
+#
+# Copyright (C) 2024 Kemeng Shi <shikemeng@xxxxxxxxxxxxxxx>
+# Copyright (C) 2024 Huawei Inc
+
+desc = """
+This is a drgn script based on wq_monitor.py to monitor writeback info on
+backing dev. For more info on drgn, visit https://github.com/osandov/drgn.
+
+ writeback(kB) Amount of dirty pages are currently being written back to
+ disk.
+
+ reclaimable(kB) Amount of pages are currently reclaimable.
+
+ dirtied(kB) Amount of pages have been dirtied.
+
+ wrttien(kB) Amount of dirty pages have been written back to disk.
+
+ avg_wb(kBps) Smoothly estimated write bandwidth of writing dirty pages
+ back to disk.
+"""
+
+import signal
+import re
+import time
+import json
+
+import drgn
+from drgn.helpers.linux.list import list_for_each_entry
+
+import argparse
+parser = argparse.ArgumentParser(description=desc,
+ formatter_class=argparse.RawTextHelpFormatter)
+parser.add_argument('bdi', metavar='REGEX', nargs='*',
+ help='Target backing device 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')
+parser.add_argument('-c', '--cgroup', action='store_true',
+ help='show writeback of bdi in cgroup')
+args = parser.parse_args()
+
+bdi_list = prog['bdi_list']
+
+WB_RECLAIMABLE = prog['WB_RECLAIMABLE']
+WB_WRITEBACK = prog['WB_WRITEBACK']
+WB_DIRTIED = prog['WB_DIRTIED']
+WB_WRITTEN = prog['WB_WRITTEN']
+NR_WB_STAT_ITEMS = prog['NR_WB_STAT_ITEMS']
+
+PAGE_SHIFT = prog['PAGE_SHIFT']
+
+def K(x):
+ return x << (PAGE_SHIFT - 10)
+
+class Stats:
+ def dict(self, now):
+ return { 'timestamp' : now,
+ 'name' : self.name,
+ 'writeback' : self.stats[WB_WRITEBACK],
+ 'reclaimable' : self.stats[WB_RECLAIMABLE],
+ 'dirtied' : self.stats[WB_DIRTIED],
+ 'written' : self.stats[WB_WRITTEN],
+ 'avg_wb' : self.avg_bw, }
+
+ def table_header_str():
+ return f'{"":>16} {"writeback":>10} {"reclaimable":>12} ' \
+ f'{"dirtied":>9} {"written":>9} {"avg_bw":>9}'
+
+ def table_row_str(self):
+ out = f'{self.name[-16:]:16} ' \
+ f'{self.stats[WB_WRITEBACK]:10} ' \
+ f'{self.stats[WB_RECLAIMABLE]:12} ' \
+ f'{self.stats[WB_DIRTIED]:9} ' \
+ f'{self.stats[WB_WRITTEN]:9} ' \
+ f'{self.avg_bw:9} '
+ return out
+
+ def show_header():
+ if Stats.table_fmt:
+ print()
+ print(Stats.table_header_str())
+
+ def show_stats(self):
+ if Stats.table_fmt:
+ print(self.table_row_str())
+ else:
+ print(self.dict(Stats.now))
+
+class WbStats(Stats):
+ def __init__(self, wb):
+ bdi_name = wb.bdi.dev_name.string_().decode()
+ # avoid to use bdi.wb.memcg_css which is only defined when
+ # CONFIG_CGROUP_WRITEBACK is enabled
+ if wb == wb.bdi.wb.address_of_():
+ ino = "1"
+ else:
+ ino = str(wb.memcg_css.cgroup.kn.id.value_())
+ self.name = bdi_name + '_' + ino
+
+ self.stats = [0] * NR_WB_STAT_ITEMS
+ for i in range(NR_WB_STAT_ITEMS):
+ if wb.stat[i].count >= 0:
+ self.stats[i] = int(K(wb.stat[i].count))
+ else:
+ self.stats[i] = 0
+
+ self.avg_bw = int(K(wb.avg_write_bandwidth))
+
+class BdiStats(Stats):
+ def __init__(self, bdi):
+ self.name = bdi.dev_name.string_().decode()
+ self.stats = [0] * NR_WB_STAT_ITEMS
+ self.avg_bw = 0
+
+ def collectStats(self, wb_stats):
+ for i in range(NR_WB_STAT_ITEMS):
+ self.stats[i] += wb_stats.stats[i]
+
+ self.avg_bw += wb_stats.avg_bw
+
+exit_req = False
+
+def sigint_handler(signr, frame):
+ global exit_req
+ exit_req = True
+
+def main():
+ # handle args
+ Stats.table_fmt = not args.json
+ interval = args.interval
+ cgroup = args.cgroup
+
+ re_str = None
+ if args.bdi:
+ for r in args.bdi:
+ 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:
+ Stats.now = time.time()
+
+ Stats.show_header()
+ for bdi in list_for_each_entry('struct backing_dev_info', bdi_list.address_of_(), 'bdi_list'):
+ bdi_stats = BdiStats(bdi)
+ if filter_re and not filter_re.search(bdi_stats.name):
+ continue
+
+ for wb in list_for_each_entry('struct bdi_writeback', bdi.wb_list.address_of_(), 'bdi_node'):
+ wb_stats = WbStats(wb)
+ bdi_stats.collectStats(wb_stats)
+ if cgroup:
+ wb_stats.show_stats()
+
+ bdi_stats.show_stats()
+ if cgroup and Stats.table_fmt:
+ print()
+
+ if interval == 0:
+ break
+ time.sleep(interval)
+
+if __name__ == "__main__":
+ main()
--
2.30.0