How jemalloc works with memory?

  allocator, c++, jemalloc

Here topic about jemalloc. I find information that memory allocated by chunks that divided in runs. And arenas curves the chunks. And we use 4*(CPU-count) arenas if CPUs more than one. What is the connection between these statements? I can’t understand how memory organized in jemalloc. What hierarchy are used here?

Source: Windows Questions C++