Use cpu_late_10ths_percent_limit to set limit on % of late tasks in 1…

…0th of a % (betaflight#13330)

* Use cpu_late_10ths_percent_limit to set limit on % of late tasks in 10th of a %
Set CPU load late limit to 1% based on testing

* Update src/main/cli/settings.c

Co-authored-by: Jan Post <[email protected]>

* Update src/main/scheduler/scheduler.h

Co-authored-by: Jan Post <[email protected]>

* Update src/main/fc/core.c

* Update src/test/unit/arming_prevention_unittest.cc

* Update src/main/scheduler/scheduler.c

---------

Co-authored-by: Mark Haslinghuis <[email protected]>
Co-authored-by: Jan Post <[email protected]>

src/main/cli/settings.c

@@ -1720,6 +1720,10 @@ const clivalue_t valueTable[] = {
     { "scheduler_relax_rx",  VAR_UINT16  | HARDWARE_VALUE, .config.minmaxUnsigned = { 0, 500 }, PG_SCHEDULER_CONFIG, PG_ARRAY_ELEMENT_OFFSET(schedulerConfig_t, 0, rxRelaxDeterminism) },
     { "scheduler_relax_osd", VAR_UINT16  | HARDWARE_VALUE, .config.minmaxUnsigned = { 0, 500 }, PG_SCHEDULER_CONFIG, PG_ARRAY_ELEMENT_OFFSET(schedulerConfig_t, 0, osdRelaxDeterminism) },
 
+#ifdef USE_LATE_TASK_STATISTICS
+    { "cpu_late_limit_permille", VAR_UINT8 | MASTER_VALUE, .config.minmaxUnsigned = { 0, 100 }, PG_SCHEDULER_CONFIG, offsetof(schedulerConfig_t, cpuLatePercentageLimit) },
+#endif
+
     { "serialmsp_halfduplex", VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP, .config.lookup = { TABLE_OFF_ON }, PG_MSP_CONFIG, offsetof(mspConfig_t, halfDuplex) },
 
 // PG_TIMECONFIG

src/main/fc/core.c

@@ -323,11 +323,13 @@ void updateArmingStatus(void)
             unsetArmingDisabled(ARMING_DISABLED_ANGLE);
         }
 
-        if (getAverageSystemLoadPercent() > LOAD_PERCENTAGE_ONE) {
+#if defined(USE_LATE_TASK_STATISTICS)
+        if ((getCpuPercentageLate() > schedulerConfig()->cpuLatePercentageLimit)) {
             setArmingDisabled(ARMING_DISABLED_LOAD);
         } else {
             unsetArmingDisabled(ARMING_DISABLED_LOAD);
         }
+#endif // USE_LATE_TASK_STATISTICS
 
         if (isCalibrating()) {
             setArmingDisabled(ARMING_DISABLED_CALIBRATING);

src/main/osd/osd.h

@@ -281,6 +281,7 @@ typedef enum {
     OSD_WARNING_RSSI_DBM,
     OSD_WARNING_OVER_CAP,
     OSD_WARNING_RSNR,
+    OSD_WARNING_LOAD,
     OSD_WARNING_COUNT // MUST BE LAST
 } osdWarningsFlags_e;
 

src/main/osd/osd_warnings.c

@@ -213,6 +213,13 @@ void renderOsdWarning(char *warningText, bool *blinking, uint8_t *displayAttr)
         return;
     }
 
+    if (osdWarnGetState(OSD_WARNING_LOAD) && (getArmingDisableFlags() & ARMING_DISABLED_LOAD)) {
+        tfp_sprintf(warningText, "CPU OVERLOAD");
+        *displayAttr = DISPLAYPORT_SEVERITY_CRITICAL;
+        *blinking = true;
+        return;
+    }
+
 #ifdef USE_GPS_RESCUE
     if (osdWarnGetState(OSD_WARNING_GPS_RESCUE_UNAVAILABLE) &&
        ARMING_FLAG(ARMED) &&

src/main/pg/scheduler.c

@@ -23,9 +23,10 @@
 #include "pg/pg_ids.h"
 #include "pg/scheduler.h"
 
-PG_REGISTER_WITH_RESET_TEMPLATE(schedulerConfig_t, schedulerConfig, PG_SCHEDULER_CONFIG, 0);
+PG_REGISTER_WITH_RESET_TEMPLATE(schedulerConfig_t, schedulerConfig, PG_SCHEDULER_CONFIG, 1);
 
 PG_RESET_TEMPLATE(schedulerConfig_t, schedulerConfig,
     .rxRelaxDeterminism = SCHEDULER_RELAX_RX,
     .osdRelaxDeterminism = SCHEDULER_RELAX_OSD,
+    .cpuLatePercentageLimit = CPU_LOAD_LATE_LIMIT
 );

src/main/pg/scheduler.h

@@ -31,9 +31,13 @@
 #define SCHEDULER_RELAX_OSD 25
 #endif
 
+// Tenths of a % of tasks late
+#define CPU_LOAD_LATE_LIMIT 10
+
 typedef struct schedulerConfig_s {
     uint16_t rxRelaxDeterminism;
     uint16_t osdRelaxDeterminism;
+    uint16_t cpuLatePercentageLimit;
 } schedulerConfig_t;
 
 PG_DECLARE(schedulerConfig_t, schedulerConfig);

src/main/scheduler/scheduler.c

@@ -69,6 +69,7 @@
 // 1 - Tasks late in last second
 // 2 - Total lateness in last second in 10ths us
 // 3 - Total tasks run in last second
+// 4 - 10ths % of tasks late in last second
 
 extern task_t tasks[];
 
@@ -107,6 +108,7 @@ static uint8_t skippedOSDAttempts = 0;
 static int16_t lateTaskCount = 0;
 static uint32_t lateTaskTotal = 0;
 static int16_t taskCount = 0;
+static uint32_t lateTaskPercentage = 0;
 static uint32_t nextTimingCycles;
 #endif
 
@@ -199,6 +201,15 @@ void taskSystemLoad(timeUs_t currentTimeUs)
 #endif
 }
 
+uint32_t getCpuPercentageLate(void)
+{
+#if defined(USE_LATE_TASK_STATISTICS)
+    return lateTaskPercentage;
+#else
+    return 0;
+#endif
+}
+
 timeUs_t checkFuncMaxExecutionTimeUs;
 timeUs_t checkFuncTotalExecutionTimeUs;
 timeUs_t checkFuncMovingSumExecutionTimeUs;
@@ -535,6 +546,10 @@ FAST_CODE void scheduler(void)
                 // Total tasks run in last second
                 DEBUG_SET(DEBUG_TIMING_ACCURACY, 3, taskCount);
 
+                lateTaskPercentage = 1000 * (uint32_t)lateTaskCount / taskCount;
+                // 10ths % of tasks late in last second
+                DEBUG_SET(DEBUG_TIMING_ACCURACY, 4, lateTaskPercentage);
+
                 lateTaskCount = 0;
                 lateTaskTotal = 0;
                 taskCount = 0;

src/main/scheduler/scheduler.h

@@ -243,6 +243,7 @@ void schedulerInit(void);
 void scheduler(void);
 timeUs_t schedulerExecuteTask(task_t *selectedTask, timeUs_t currentTimeUs);
 void taskSystemLoad(timeUs_t currentTimeUs);
+uint32_t getCpuPercentageLate(void);
 void schedulerEnableGyro(void);
 uint16_t getAverageSystemLoadPercent(void);
 float schedulerGetCycleTimeMultiplier(void);

src/test/unit/arming_prevention_unittest.cc

@@ -1161,4 +1161,5 @@ extern "C" {
         return 0.0f;
     }
     void getRcDeflectionAbs(void) {}
+    uint32_t getCpuPercentageLate(void) { return 0; };
 }