64G内存的服务器，应该给elasticsearch分配多少？

我通过docker-compose启动elasticsearch，docker-compose.yml文件里ES_JAVA_OPTS变量的值，给-Xms和-Xmx都是512M，是不是太小了？
完整docker-compose.yml的内容如下：

version: '2.2'

services:

  es01:

    image: docker.elastic.co/elasticsearch/elasticsearch:7.2.1

    container_name: es01

    environment:

      - node.name=es01

      - discovery.seed_hosts=es02

      - cluster.initial_master_nodes=es01,es02

      - cluster.name=docker-cluster

      - bootstrap.memory_lock=true

      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"

    ulimits:

      memlock:

        soft: -1

        hard: -1

    volumes:

      - esdata01:/usr/share/elasticsearch/data

    ports:

      - 9200:9200

    networks:

      - esnet

  es02:

    image: docker.elastic.co/elasticsearch/elasticsearch:7.2.1

    container_name: es02

    environment:

      - node.name=es02

      - discovery.seed_hosts=es01

      - cluster.initial_master_nodes=es01,es02

      - cluster.name=docker-cluster

      - bootstrap.memory_lock=true

      - "ES_JAVA_OPTS=-Xms512m -Xmx512m"

    ulimits:

      memlock:

        soft: -1

        hard: -1

    volumes:

      - esdata02:/usr/share/elasticsearch/data

    networks:

      - esnet



volumes:

  esdata01:

    driver: local

  esdata02:

    driver: local



networks:

  esnet: