the personal understanding about JAVA Heap space and GC

these days,i try to summarize  knowledge in my five past years .this morning i just  restudied the JVM (Java Virtual Machine). actually before this because the reason of job,i did not know it well . let us just get straight to the point.

  the space of heap . there are three parts compose its heap space,  heap space= new generation space+old generation space+ Permanent space.

new generation space= one Eden space + two survivor spaces  

old generation space=tenure space

permanent space=  perm read only ,perm read write

the process of GC goes like: JVM initially  allocates memories  of  all objects in Eden space, when Eden space is full, JVM moves those objects which are still referred  not "dead object" to one of the survivor  space, when GC carries a minor garbage collection . those objects still alive in survivor space move to the tenure space.when the tenure is full .GC will take a slowly full garbage clearness .it usually take a lot of time