dumpsys meminfo 说明

PSS: PSS differs from RSS in that it reports the proportional size of its shared libraries, i.e. if three processes all use a shared library that has 30 pages, that library will only 

contribute 10 pages to the PSS that is reported for each of the three processes. PSS is a very useful number because when the PSS for all processes in the system are 

summed together, that is a good representation for the total memory usage in the system. When a process is killed, the shared libraries that contributed to its PSS will 

be proportionally distributed to the PSS totals for the remaining processes still using that library. In this way PSS can be slightly misleading, because when a process is 

killed, PSS does not accurately represent the memory returned to the overall system.

PSS：实际使用的物理内存（比例分配共享库占用的内存）

Pss：它是把共享内存根据一定比例分摊到共享它的各个进程来计算所得到进程使用内存。

 PrivateDirty：它是指非共享的，又不能换页出去（can not be paged to disk ）的内存的大小。比如Linux为了提高分配内存速度而缓冲的小对象，即使你的进程结束，该内存也不会释放掉，它只是又重新回到缓冲中而已。

SharedDirty:参照PrivateDirty我认为它应该是指共享的，又不能换页出去（can not be paged to disk ）的内存的大小。比如Linux为了提高分配内存速度而缓冲的小对象，即使所有共享它的进程结束，该内存也不会释放掉，它只是又重新回到缓冲中而已。