Further work on issue #18640385: Add procstats test mode

Tune sampling periods:

- Lower minimum sample interval when in test mode.
- Add a check when sampling pss to make sure this is at least 1
  second since the pss changed, to reduce the amount of bad
  data (very small pss samples) that we see.

Change-Id: I624a7d0480f3f6b22d229744e028d13a2c7b0e89

2 files changed, 16 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 1227148..82afeed 100755
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -1841,7 +1841,9 @@ public final class ActivityManagerService extends ActivityManagerNative
                         proc = mPendingPssProcesses.remove(0);
                         procState = proc.pssProcState;
                         lastPssTime = proc.lastPssTime;
-                        if (proc.thread != null && procState == proc.setProcState) {
+                        if (proc.thread != null && procState == proc.setProcState
+                                && (lastPssTime+ProcessList.PSS_SAFE_TIME_FROM_STATE_CHANGE)
+                                        < SystemClock.uptimeMillis()) {
                             pid = proc.pid;
                         } else {
                             proc = null;
@@ -17746,7 +17748,8 @@ public final class ActivityManagerService extends ActivityManagerNative
                     + (app.nextPssTime-now) + ": " + app);
         } else {
             if (now > app.nextPssTime || (now > (app.lastPssTime+ProcessList.PSS_MAX_INTERVAL)
-                    && now > (app.lastStateTime+ProcessList.PSS_MIN_TIME_FROM_STATE_CHANGE))) {
+                    && now > (app.lastStateTime+ProcessList.minTimeFromStateChange(
+                    mTestPssMode)))) {
                 requestPssLocked(app, app.setProcState);
                 app.nextPssTime = ProcessList.computeNextPssTime(app.curProcState, false,
                         mTestPssMode, isSleeping(), now);
diff --git a/services/core/java/com/android/server/am/ProcessList.java b/services/core/java/com/android/server/am/ProcessList.java
index aa86786..4ac6684 100644
--- a/services/core/java/com/android/server/am/ProcessList.java
+++ b/services/core/java/com/android/server/am/ProcessList.java
@@ -411,7 +411,10 @@ final class ProcessList {
         sb.append(ramKb);
     }
 
-    // The minimum amount of time after a state change it is safe ro collect PSS.
+    // How long after a state change that it is safe to collect PSS without it being dirty.
+    public static final int PSS_SAFE_TIME_FROM_STATE_CHANGE = 1000;
+
+    // The minimum time interval after a state change it is safe to collect PSS.
     public static final int PSS_MIN_TIME_FROM_STATE_CHANGE = 15*1000;
 
     // The maximum amount of time we want to go between PSS collections.
@@ -441,6 +444,9 @@ final class ProcessList {
     // The amount of time until PSS when a cached process stays in the same state.
     private static final int PSS_SAME_CACHED_INTERVAL = 30*60*1000;
 
+    // The minimum time interval after a state change it is safe to collect PSS.
+    public static final int PSS_TEST_MIN_TIME_FROM_STATE_CHANGE = 10*1000;
+
     // The amount of time during testing until PSS when a process first becomes top.
     private static final int PSS_TEST_FIRST_TOP_INTERVAL = 3*1000;
 
@@ -548,6 +554,10 @@ final class ProcessList {
         return sProcStateToProcMem[procState1] != sProcStateToProcMem[procState2];
     }
 
+    public static long minTimeFromStateChange(boolean test) {
+        return test ? PSS_TEST_MIN_TIME_FROM_STATE_CHANGE : PSS_MIN_TIME_FROM_STATE_CHANGE;
+    }
+
     public static long computeNextPssTime(int procState, boolean first, boolean test,
             boolean sleeping, long now) {
         final long[] table = test