Valentin V. Bartenev
a9273f02bb
The previous implementation maintained three exponential moving averages (1/5/15-minute) of CPU busy-fraction, sampled every 5 seconds. This had two problems: 1. Wrong semantics: the metric was labelled "load_avg" (a Unix concept measuring run-queue depth), but the tracker actually measures CPU busy-time as a fraction of FreeRTOS ticks — i.e. utilization, not load. The name was misleading. 2. Poor responsiveness: the 1-minute EMA (DECAY = exp(-5/60) ≈ 0.920) has a ~60-second time constant. On a live web panel, this made the metric appear frozen, especially during short bursts of activity (e.g. an HTTP request from the panel itself). This commit replaces the EMA with a 64-sample simple moving average (SMA) over a compact uint8_t circular buffer. The sample interval is 60 s / 64 = 937,500 µs, so the window covers exactly 60 seconds: Algorithm: - Every 937,500 µs (= 60 s / 64), the FreeRTOS tick delta (busy vs idle ticks on core 0) is computed and stored as a uint8_t (0–255 = 0–100% utilization). - The circular buffer holds 64 samples, spanning exactly 60 seconds (64 × 937,500 µs = 60,000,000 µs). The timer interval is derived directly from the window size: 60 000 000 / SMA_WINDOW µs. - The index wraps with a bitwise AND (& 63) instead of modulo, since 64 is a power of 2. - The running sum is a uint16_t (max 64 × 255 = 16 320, fits easily). - The result _sma_avg is a volatile float written atomically by the esp_timer task (core 0) and read from the main loop (core 1). No spinlock is needed: on Xtensa LX7, a 32-bit aligned float store is a single instruction. The 60-second window smooths out short bursts (e.g. WiFi/HTTP spikes) while reacting to sustained load changes within ~10–15 seconds. Naming: - The public API is now getCore0Util() returning a float in [0.0, 1.0]. The name explicitly identifies which core is measured (core 0, which runs WiFi, MQTT, HTTP, and LwIP — see task_pinning.c). - JSON keys: "load_avg" (array) → "core0_util" (scalar float, percent) - HistorySample field: load_avg1_pct → core0_util_pct - StatsHistory series key: "cpu_load" → "core0_util" - Web panel label: "Load Avg" → "Core0 Util" The history snapshot (once per minute) reads the same _sma_avg value, which at that point represents the rolling average of the last 60 seconds — exactly one history interval.
41 строка
802 B
C++
41 строка
802 B
C++
#pragma once
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#ifdef ESP32
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#include <stdint.h>
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#include "esp_attr.h"
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#include "esp_timer.h"
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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class CPUUsageTracker {
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public:
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void begin();
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float getCore0Util() const { return _sma_avg; }
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private:
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static constexpr uint8_t SMA_WINDOW = 64; // power of 2 — enables & mask
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static volatile uint32_t s_idle_ticks;
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static volatile uint32_t s_busy_ticks;
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static TaskHandle_t s_idle_handle;
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static void IRAM_ATTR s_tick_hook();
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static void s_sample_cb(void* arg);
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uint32_t _last_idle = 0;
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uint32_t _last_busy = 0;
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uint8_t _sma_buf[SMA_WINDOW] = {};
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uint16_t _sma_sum = 0;
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uint8_t _sma_idx = 0;
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volatile float _sma_avg = 0.0f;
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esp_timer_handle_t _timer = nullptr;
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void _onSample();
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};
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#endif
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