clocksync: expose transmit_extra as a tunable [danger_options] knob

klippy/clocksync.py

@@ -9,7 +9,11 @@
 
 RTT_AGE = 0.000010 / (60.0 * 60.0)
 DECAY = 1.0 / 30.0
-TRANSMIT_EXTRA = 0.001
+# Default forward-scheduling headroom added to the clock estimate sent
+# to the serialqueue.  Can be overridden via [danger_options]
+# transmit_extra.  Increase this (e.g. to 0.003-0.005) if you
+# experience 'Timer too close' shutdowns on a heavily loaded host.
+TRANSMIT_EXTRA = 0.002
 
 
 class ClockSync:
@@ -30,6 +34,11 @@ def __init__(self, reactor):
         self.clock_avg = self.clock_covariance = 0.0
         self.prediction_variance = 0.0
         self.last_prediction_time = 0.0
+        self.transmit_extra = TRANSMIT_EXTRA
+
+    def set_transmit_extra(self, value):
+        """Override the transmit_extra headroom (called from danger_options)."""
+        self.transmit_extra = value
 
     def disconnect(self):
         self.reactor.update_timer(self.get_clock_timer, self.reactor.NEVER)
@@ -145,7 +154,7 @@ def _handle_clock(self, params):
         pred_stddev = math.sqrt(self.prediction_variance)
         self.serial.set_clock_est(
             new_freq,
-            self.time_avg + TRANSMIT_EXTRA,
+            self.time_avg + self.transmit_extra,
             int(self.clock_avg - 3.0 * pred_stddev),
             clock,
         )
@@ -192,7 +201,7 @@ def dump_debug(self):
             "clocksync state: mcu_freq=%d last_clock=%d"
             " clock_est=(%.3f %d %.3f) min_half_rtt=%.6f min_rtt_time=%.3f"
             " time_avg=%.3f(%.3f) clock_avg=%.3f(%.3f)"
-            " pred_variance=%.3f"
+            " pred_variance=%.3f transmit_extra=%.6f"
             % (
                 self.mcu_freq,
                 self.last_clock,
@@ -206,6 +215,7 @@ def dump_debug(self):
                 self.clock_avg,
                 self.clock_covariance,
                 self.prediction_variance,
+                self.transmit_extra,
             )
         )
 

klippy/extras/danger_options.py

@@ -1,3 +1,6 @@
+from ..clocksync import TRANSMIT_EXTRA
+
+
 class DangerOptions:
     def __init__(self, config):
         self.minimal_logging = config.getboolean("minimal_logging", False)
@@ -38,6 +41,14 @@ def __init__(self, config):
         self.homing_elapsed_distance_tolerance = config.getfloat(
             "homing_elapsed_distance_tolerance", 0.5, minval=0.0
         )
+        # transmit_extra: forward-scheduling headroom (seconds) added to the
+        # MCU clock estimate passed to the serialqueue.  Increasing this helps
+        # prevent 'Timer too close' MCU shutdowns on hosts that experience CPU
+        # or scheduling jitter.  See docs/Config_Reference.md ([danger_options])
+        # for guidance.
+        self.transmit_extra = config.getfloat(
+            "transmit_extra", TRANSMIT_EXTRA, minval=0.0, maxval=0.010
+        )
 
         temp_ignore_limits = False
         if config.getboolean("temp_ignore_limits", None) is None:
@@ -78,4 +89,20 @@ def get_danger_options():
 def load_config(config):
     global DANGER_OPTIONS
     DANGER_OPTIONS = DangerOptions(config)
+    # Apply transmit_extra to all ClockSync instances already registered
+    printer = config.get_printer()
+    # Wire transmit_extra into MCU clocksync objects at connect time
+    printer.register_event_handler(
+        "klippy:mcu_identify",
+        lambda: _apply_transmit_extra(printer, DANGER_OPTIONS.transmit_extra),
+    )
     return DANGER_OPTIONS
+
+
+def _apply_transmit_extra(printer, value):
+    """Push transmit_extra into all MCU clocksync objects."""
+    for name, obj in printer.objects.items():
+        if name == "mcu" or name.startswith("mcu "):
+            clocksync = getattr(obj, "_clocksync", None)
+            if clocksync is not None and hasattr(clocksync, "set_transmit_extra"):
+                clocksync.set_transmit_extra(value)