为什么在Java内存转储分析器中堆总数与内存设置和JVM的总使用量不一致?

We use Eclipse memory analyzer for Java (Tomcat Web application) dump. The total heap in the resulting piechart is shown as 86 Mb. At the same time the heap limit for that JVM is set at 1.5GB and we saw the total JVM usage going up to 2.8 GB. We use Eclipse memory analyzer for Java (Tomcat