query about “dumpsys meminfo” in android

Question

When I run "adb shell dumpsys meminfo" on android 4.2, I get the result like

  Shared Private Heap Heap Heap Pss Dirty Dirty Size Alloc Free ------ ------ ------ ------ ------ ------ Native 28 8 28 16404 12256 3663 Dalvik 14062 10060 13736 20032 15254 4778 Cursor 0 0 0 Ashmem 0 0 0 Other dev 4762 9556 0 .so mmap 11699 1824 1500 .jar mmap 0 0 0 .apk mmap 368 0 0 .ttf mmap 811 0 0 .dex mmap 3736 0 0 Other mmap 114 16 32 Unknown 12064 544 12052 TOTAL 47644 22008 27348 36436 27510 8441 

I have read the page of How do I discover memory usage of my application in Android? , but still have several questions:

• Why the native Pss, shared dirty private dirty is very small?
• the heap size should be smaller than Pss?
• What does Unknown mean? Seems very big.
• If I want to know how much memory my app uses, which data should I use? The Total Pss? But it doesn't include the native Pss which is nealy zero?

Answer 1

Please refer to the question How do I discover memory usage of my application in Android? . I would also like you to refer to Detail VSS,RSS,PSS,USS link. The most appropriate data to use for a particular app is USS (Unique Set Size ) as

USS is the total private memory for a process, ie that memory that is completely unique to that process . USS is an extremely useful number because it indicates the true incremental cost of running a particular process. When a process is killed, the USS is the total memory that is actually returned to the system. USS is the best number to watch when initially suspicious of memory leaks in a process.

which you can get by adb shell procrank | grep <your.package.name> adb shell procrank | grep <your.package.name>