Why dumpsys meminfo returns Pss (KB) is Zero?

Question

I want to analysis my app memory. But when I use adb dumpsys meminfo myapp it returns:

 App Summary
                       Pss(KB)
                        ------
           Java Heap:        0
         Native Heap:        0
                Code:        0
               Stack:        0
            Graphics:        0
       Private Other:        0
              System:        0

               TOTAL:        0       TOTAL SWAP PSS:        0

 Objects
               Views:       20         ViewRootImpl:        1
         AppContexts:        3           Activities:        1
              Assets:        2        AssetManagers:        2
       Local Binders:       10        Proxy Binders:       16
       Parcel memory:        6         Parcel count:       25
    Death Recipients:        0      OpenSSL Sockets:        0
            WebViews:        0

myapp

It has an activity message, but Pss is 0;

And when I dumpsys meninfo systemapp like settings:

 App Summary
                       Pss(KB)
                        ------
           Java Heap:     3264
         Native Heap:     5404
                Code:    10172
               Stack:       40
            Graphics:        0
       Private Other:     1916
              System:    12551

               TOTAL:    33347       TOTAL SWAP PSS:        0

 Objects
               Views:      110         ViewRootImpl:        1
         AppContexts:        3           Activities:        1
              Assets:        2        AssetManagers:        2
       Local Binders:       29        Proxy Binders:       28
       Parcel memory:        4         Parcel count:       18
    Death Recipients:        0      OpenSSL Sockets:        0
            WebViews:        0

settings