instance CPU usage exceeds 100% in 8.3.0

[amwyyyy]

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The cpu usage rate exceeds 100%. From the source code of the agent, it will not exceed 100%. What might be the cause?

    public CPU getCPUMetrics() {
        long cpuTime = this.getCpuTime();
        long cpuCost = cpuTime - lastCPUTimeNs;
        long now = System.nanoTime();

        try {
            CPU.Builder cpuBuilder = CPU.newBuilder();
            return cpuBuilder.setUsagePercent(cpuCost * 1.0d / ((now - lastSampleTimeNs) * cpuCoreNum) * 100).build();
        } finally {
            lastCPUTimeNs = cpuTime;
            lastSampleTimeNs = now;
        }
    }