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server-config/services/monero/xmrig-auto-pause.py

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6.8 KiB
Python

#!/usr/bin/env python3
"""
Auto-pause xmrig when other services need CPU.
Monitors non-nice CPU usage from /proc/stat. Since xmrig runs at Nice=19,
its CPU time lands in the 'nice' column and is excluded from the metric.
When real workload (user + system + irq + softirq) exceeds the threshold,
stops xmrig. When it drops below threshold for GRACE_PERIOD seconds,
restarts xmrig.
This replaces per-service pause scripts with a single general-purpose
monitor that handles any CPU-intensive workload (gitea workers, llama-cpp
inference, etc.) without needing to know about specific processes.
Why scheduler priority alone isn't enough:
Nice=19 / SCHED_IDLE only affects which thread gets the next time slice.
RandomX's 2MB-per-thread scratchpad (24MB across 12 threads) pollutes
the shared 32MB L3 cache, and its memory access pattern saturates DRAM
bandwidth. Other services run slower even though they aren't denied CPU
time. The only fix is to stop xmrig entirely when real work is happening.
"""
import os
import subprocess
import sys
import time
POLL_INTERVAL = int(os.environ.get("POLL_INTERVAL", "3"))
GRACE_PERIOD = float(os.environ.get("GRACE_PERIOD", "15"))
# Percentage of total CPU ticks that non-nice processes must use to trigger
# a pause. On a 12-thread system, one fully loaded core ≈ 8.3% of total.
# Default 5% catches anything using more than ~60% of a single core.
CPU_THRESHOLD = float(os.environ.get("CPU_THRESHOLD", "5"))
# After starting xmrig, ignore CPU spikes for this many seconds to let
# RandomX dataset initialization complete (~4s on the target hardware)
# without retriggering a stop.
STARTUP_COOLDOWN = float(os.environ.get("STARTUP_COOLDOWN", "10"))
# Directory for persisting pause state across script restarts. Without
# this, a restart while xmrig is paused loses the paused_by_us flag and
# xmrig stays stopped permanently.
STATE_DIR = os.environ.get("STATE_DIR", "")
_PAUSE_FILE = os.path.join(STATE_DIR, "paused") if STATE_DIR else ""
def log(msg):
print(f"[xmrig-auto-pause] {msg}", file=sys.stderr, flush=True)
def read_cpu_ticks():
"""Read CPU tick counters from /proc/stat.
Returns (total_ticks, real_work_ticks) where real_work excludes the
'nice' column (xmrig) and idle/iowait.
"""
with open("/proc/stat") as f:
parts = f.readline().split()
# cpu user nice system idle iowait irq softirq steal
user, nice, system, idle, iowait, irq, softirq, steal = (
int(x) for x in parts[1:9]
)
total = user + nice + system + idle + iowait + irq + softirq + steal
real_work = user + system + irq + softirq
return total, real_work
def is_active(unit):
"""Check if a systemd unit is currently active."""
result = subprocess.run(
["systemctl", "is-active", "--quiet", unit],
capture_output=True,
)
return result.returncode == 0
def systemctl(action, unit):
result = subprocess.run(
["systemctl", action, unit],
capture_output=True,
text=True,
)
if result.returncode != 0:
log(f"systemctl {action} {unit} failed (rc={result.returncode}): {result.stderr.strip()}")
return result.returncode == 0
def _save_paused(paused):
"""Persist pause flag so a script restart can resume where we left off."""
if not _PAUSE_FILE:
return
try:
if paused:
open(_PAUSE_FILE, "w").close()
else:
os.remove(_PAUSE_FILE)
except OSError:
pass
def _load_paused():
"""Check if a previous instance left xmrig paused."""
if not _PAUSE_FILE:
return False
return os.path.isfile(_PAUSE_FILE)
def main():
paused_by_us = _load_paused()
idle_since = None
started_at = None # monotonic time when we last started xmrig
prev_total = None
prev_work = None
if paused_by_us:
log("Recovered pause state from previous instance")
log(
f"Starting: poll={POLL_INTERVAL}s grace={GRACE_PERIOD}s "
f"threshold={CPU_THRESHOLD}% cooldown={STARTUP_COOLDOWN}s"
)
while True:
total, work = read_cpu_ticks()
if prev_total is None:
prev_total = total
prev_work = work
time.sleep(POLL_INTERVAL)
continue
dt = total - prev_total
if dt <= 0:
prev_total = total
prev_work = work
time.sleep(POLL_INTERVAL)
continue
real_work_pct = ((work - prev_work) / dt) * 100
prev_total = total
prev_work = work
# Don't act during startup cooldown — RandomX dataset init causes
# a transient CPU spike that would immediately retrigger a stop.
if started_at is not None:
if time.monotonic() - started_at < STARTUP_COOLDOWN:
time.sleep(POLL_INTERVAL)
continue
# Cooldown expired — verify xmrig survived startup. If it
# crashed during init (hugepage failure, pool unreachable, etc.),
# re-enter the pause/retry cycle rather than silently leaving
# xmrig dead.
if not is_active("xmrig.service"):
log("xmrig died during startup cooldown — will retry")
paused_by_us = True
_save_paused(True)
started_at = None
busy = real_work_pct > CPU_THRESHOLD
if busy:
idle_since = None
if paused_by_us and is_active("xmrig.service"):
# Something else restarted xmrig (deploy, manual start, etc.)
# while we thought it was stopped. Reset ownership so we can
# manage it again.
log("xmrig was restarted externally while paused — reclaiming")
paused_by_us = False
_save_paused(False)
if not paused_by_us:
# Only claim ownership if xmrig is actually running.
# If something else stopped it (e.g. UPS battery hook),
# don't interfere — we'd wrongly restart it later.
if is_active("xmrig.service"):
log(f"Real workload detected ({real_work_pct:.1f}% CPU) — stopping xmrig")
if systemctl("stop", "xmrig.service"):
paused_by_us = True
_save_paused(True)
else:
if paused_by_us:
if idle_since is None:
idle_since = time.monotonic()
elif time.monotonic() - idle_since >= GRACE_PERIOD:
log(f"Workload ended ({real_work_pct:.1f}% CPU) past grace period — starting xmrig")
if systemctl("start", "xmrig.service"):
paused_by_us = False
_save_paused(False)
started_at = time.monotonic()
idle_since = None
time.sleep(POLL_INTERVAL)
if __name__ == "__main__":
main()