Overview 面板重要监控指标详解

https://docs.pingcap.com/zh/tidb/v4.0/grafana-overview-dashboard#pd

https://docs.pingcap.com/zh/tidb/v4.0/pd-scheduling-best-practices#pd-调度策略最佳实践

region heartbeat，每个tikv上报pd的心跳，如果心跳上报过多，超过10w，考虑扩容kv，或者尝试静默region，结合99% region health latency 判断