Off-heap memory is used a lot more than specified pagecache size

Neo4j Graph Platform
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  • 4.4.4 community edition

Hi,
I have questions on off-heap memory consumption by neo4j.
We have quite big indexes in neo4j db as below.

  • Total size of data and native indexes in all databases: 157600m

And we set neo4j configuraion as follows :

  heap_initial_size: 100G
  heap_max_size: 100G
  pagecache_size: 150G
  transaction_database_max_size: 70G

Although heap size + pagecache_size is 250G(100G + 150G), a lot more memory is being used(approx. 430G).
When we checked jvm heap, it seems heap size being used was lower than 100G, so I think most of extra consumption would be in off-heap memory.

I want to know why off-heap memory is used a lot more than specified pagecache size.
If there's some reason, is there any way to reduce it's consumption?

Thank you in advance.