Android TrafficStats.getTotalRxBytes() is less than expected

问题

I'm trying to get а real traffic stats data. But, TrafficStats.getTotalRxBytes() is less than a sum of TrafficStats.getUidRxBytes() for each installed application. I've found it out by running each 30 seconds this code (being on a Wi-Fi network):

long total = TrafficStats.getTotalRxBytes();
long mobileTotal = TrafficStats.getMobileRxBytes();
long wifiTotal = (total - mobileTotal);
Log.v("SSS", "total=" + total + " mob=" + mobileTotal + " wifi=" + wifiTotal);

ArrayList<Integer> uids = new ArrayList<Integer>();
int cnt = 0;
for (ApplicationInfo appInfo : packageManager.getInstalledApplications(0)) {
  long bytes = TrafficStats.getUidRxBytes(appInfo.uid);
  if (!uids.contains(appInfo.uid)) {
    // few applications can refer to same uid - sum each uid stats only once
    uids.add(appInfo.uid);
    if (bytes > 0) cnt += bytes;
  }
}
Log.v("SSS", "sum traffic stats = " + cnt);

And this is in logs:

12-12 19:43:18.798: V/SSS(4772): total=4245863 mob=0 wifi=4245863
12-12 19:43:19.569: V/SSS(4772): sum traffic stats = 9313461
12-12 19:43:49.628: V/SSS(4772): total=4245915 mob=0 wifi=4245915
12-12 19:43:50.459: V/SSS(4772): sum traffic stats = 9314216
12-12 19:44:20.518: V/SSS(4772): total=4246524 mob=0 wifi=4246524
12-12 19:44:21.439: V/SSS(4772): sum traffic stats = 9320030

The difference between totals is less than difference between sums :

9320030 - 9314216 = 5814 bytes // sums of traffic stats by uid
4246524 - 4245915 = 609 bytes // total traffic stats

1) Why is that? 2) How do i get a correct value for total traffic stats - should i just sum traffic stats by uids?

来源：https://stackoverflow.com/questions/8478696/android-trafficstats-gettotalrxbytes-is-less-than-expected

标签

android

traffic