Although I find a lot topies about this question, but I still feel confused about the difference between the api in SDK and usage of dumpsys meminfo. I am sorry.
I'am writting an android demo to monitor its own memory usage. Firstly: I will malloc some memory in native layer; secondly: In my java layer code in MainActivity, I create an independent thread to monitor memory usage, the code is like this:
int[] pids = {android.os.Process.myPid()};
// For debug
while (true && !exit) {
ActivityManager activityManager = (ActivityManager)getSystemService(ACTIVITY_SERVICE);
Debug.MemoryInfo[] mem_info_list = activityManager.getProcessMemoryInfo(pids);
Log.println(Log.DEBUG, "com.test.faultinject", "pids = " + Arrays.toString(pids));
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalPrivateClean = " + mem_info_list[0].getTotalPrivateClean()/1024 + "MB");
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalPrivateDirty = " + mem_info_list[0].getTotalPrivateDirty()/1024 + "MB");
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalPss = " + mem_info_list[0].getTotalPss()/1024 + "MB");
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalSharedClean = " + mem_info_list[0].getTotalSharedClean()/1024 + "MB");
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalSharedDirty = " + mem_info_list[0].getTotalPrivateDirty()/1024 + "MB");
Log.println(Log.DEBUG, "com.test.faultinject", "getTotalSwappablePss = " + mem_info_list[0].getTotalSwappablePss()/1024 + "MB");
SystemClock.sleep(1000);
}
when running this application, we can found the log in logcat like below:
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: pids = [22273]
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateClean = 2MB
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateDirty = 44MB
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalPss = 52MB
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedClean = 74MB
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedDirty = 44MB
2021-04-02 11:24:52.947 22273-22316/com.test.mytest D/com.test.mytest: getTotalSwappablePss = 2MB
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: pid = 22273
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: pids = [22273]
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateClean = 2MB
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateDirty = 44MB
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: getTotalPss = 52MB
2021-04-02 11:24:53.952 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedClean = 74MB
2021-04-02 11:24:53.953 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedDirty = 44MB
2021-04-02 11:24:53.953 22273-22316/com.test.mytest D/com.test.mytest: getTotalSwappablePss = 2MB
2021-04-02 11:24:54.957 22273-22316/com.test.mytest D/com.test.mytest: pid = 22273
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: pids = [22273]
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateClean = 2MB
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateDirty = 44MB
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalPss = 52MB
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedClean = 74MB
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedDirty = 44MB
2021-04-02 11:24:54.958 22273-22316/com.test.mytest D/com.test.mytest: getTotalSwappablePss = 2MB
we can see that getTotalPss function always return 54MB. At this time, I use dumpsys meminfo 22273 to dump memory info in adb shell, the result is like this:
PD1824:/ $ dumpsys meminfo 22273
Applications Memory Usage (in Kilobytes):
Uptime: 462065977 Realtime: 546694666
** MEMINFO in pid 22273 [com.test.mytest] **
Pss Private Private SwapPss Heap Heap Heap
Total Dirty Clean Dirty Size Alloc Free
------ ------ ------ ------ ------ ------ ------
Native Heap 133751 133684 0 40 149504 143317 6186
Dalvik Heap 2660 2640 0 24 14305 2017 12288
Dalvik Other 896 892 0 0
Stack 64 64 0 0
Ashmem 2 0 0 0
Gfx dev 2332 2332 0 0
Other dev 19 4 12 0
.so mmap 5036 216 1796 8
.jar mmap 1970 0 340 0
.apk mmap 565 0 40 0
.ttf mmap 289 0 128 0
.dex mmap 2384 2384 0 0
.oat mmap 56 0 0 0
.art mmap 6296 5924 0 35
Other mmap 495 160 0 0
Unknown 953 908 0 5
TOTAL 157880 149208 2316 112 163809 145334 18474
App Summary
Pss(KB)
------
Java Heap: 8564
Native Heap: 133684
Code: 4904
Stack: 64
Graphics: 2332
Private Other: 1976
System: 6356
TOTAL: 157880 TOTAL SWAP PSS: 112
Objects
Views: 60 ViewRootImpl: 1
AppContexts: 6 Activities: 1
Assets: 11 AssetManagers: 0
Local Binders: 16 Proxy Binders: 36
Parcel memory: 4 Parcel count: 16
Death Recipients: 2 OpenSSL Sockets: 0
WebViews: 0
SQL
MEMORY_USED: 0
PAGECACHE_OVERFLOW: 0 MALLOC_SIZE: 0
We can see that the TOTAL PSS is 157880KB, it is not the same with the result return by getTotalPss function. And actually, the real memory is more close to result of dumpsys.
But after a few minutes, we can see that getTotalPss function return value is almost closed to result of dumpsys:
2021-04-02 11:31:02.823 22273-22316/com.test.mytest D/com.test.mytest: pid = 22273
2021-04-02 11:31:02.823 22273-22316/com.test.mytest D/com.test.mytest: pids = [22273]
2021-04-02 11:31:02.823 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateClean = 2MB
2021-04-02 11:31:02.823 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateDirty = 146MB
2021-04-02 11:31:02.824 22273-22316/com.test.mytest D/com.test.mytest: getTotalPss = 155MB
2021-04-02 11:31:02.824 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedClean = 74MB
2021-04-02 11:31:02.824 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedDirty = 146MB
2021-04-02 11:31:02.824 22273-22316/com.test.mytest D/com.test.mytest: getTotalSwappablePss = 2MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: pid = 22273
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: pids = [22273]
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateClean = 2MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalPrivateDirty = 146MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalPss = 155MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedClean = 74MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalSharedDirty = 146MB
2021-04-02 11:31:03.828 22273-22316/com.test.mytest D/com.test.mytest: getTotalSwappablePss = 2MB
Can anybody tell me what is the different between Debug.MemoryInfo.getTotalPss() function and the result of dumpsys meminfo? And why getTotalPss() function cannot get real result as soon as dumpsys? Thank you very much!
Update on 2021-04-09
The android system of my test device is Android10. I try to read source code of ActivityManager::getProcessMemoryInfo, it has a limited rate to get memory info from native:
And we find that the inteval of this function is set to 5mins default:
I feel confuse why the inteval is so long and if we can change the inteval?
