The pmap(1) utility will show, for each mapping of a given process, the starting byte address in the process's address
space, the size, the RSS (size of the mapping in physical memory), the amount of dirty pages, the permission, the
device node, the offset, and the file backing the mapping, if any.
As the last line of output, the pmap(1) utility will tally up the total size of all mappings as well as show the total
size of writable/private mappings and of shared mappings.
pmap工具显示每个进程地址空间的映射，进程地址空间的开始地址，大小，映射物理内存的大小，脏页的数量，权限，设备节点，位移，如果有的话，显示映射的文件。