Static CPU_TOTAL_TICKS 

static CPU_TOTAL_TICKS: [AtomicU64; 32]

Per-CPU scheduler tick counters used for CPU usage estimation.

• CPU_TOTAL_TICKS[cpu]: all timer ticks observed on cpu.
• CPU_IDLE_TICKS[cpu]: ticks where the idle task was running on cpu.

CPU usage over a time window: usage = 1 - (delta_idle / delta_total).