From 09138ccf3d11987a358853723dcfa87cc378e1d0 Mon Sep 17 00:00:00 2001
From: Kalesh Singh <kaleshsingh@google.com>
Date: Fri, 11 Nov 2022 11:48:01 -0800
Subject: [PATCH] AMS: Add Phenotype key for low swap threshold

KEY_LOW_SWAP_THRESHOLD_PERCENT controls the minimum percentage
of free swap imposed by proactive kills.

Bug: 249601646
Test: adb shell device_config put activity_manager low_swap_threshold_percent 0.50
Test: adb shell device_config get activity_manager low_swap_threshold_percent
Change-Id: Ieadd31efc677b43ce008a3b26726b565e9f497ab
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 .../server/am/ActivityManagerConstants.java   | 22 +++++++++++++++++++
 .../com/android/server/am/OomAdjuster.java    |  2 +-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/services/core/java/com/android/server/am/ActivityManagerConstants.java b/services/core/java/com/android/server/am/ActivityManagerConstants.java
index 4f207a76a4d5b..003f7f0d88fb7 100644
--- a/services/core/java/com/android/server/am/ActivityManagerConstants.java
+++ b/services/core/java/com/android/server/am/ActivityManagerConstants.java
@@ -253,6 +253,13 @@ final class ActivityManagerConstants extends ContentObserver {
      */
     private static final String KEY_PROACTIVE_KILLS_ENABLED = "proactive_kills_enabled";
 
+    /**
+      * Trim LRU cached app when swap falls below this minimum percentage.
+      *
+      * Depends on KEY_PROACTIVE_KILLS_ENABLED
+      */
+    private static final String KEY_LOW_SWAP_THRESHOLD_PERCENT = "low_swap_threshold_percent";
+
     /**
      * Default value for mFlagBackgroundActivityStartsEnabled if not explicitly set in
      * Settings.Global. This allows it to be set experimentally unless it has been
@@ -881,6 +888,8 @@ final class ActivityManagerConstants extends ContentObserver {
 
     private static final boolean DEFAULT_PROACTIVE_KILLS_ENABLED = false;
 
+    private static final float DEFAULT_LOW_SWAP_THRESHOLD_PERCENT = 0.10f;
+
     private static final String KEY_MIN_ASSOC_LOG_DURATION = "min_assoc_log_duration";
 
     public static long MIN_ASSOC_LOG_DURATION = DEFAULT_MIN_ASSOC_LOG_DURATION;
@@ -912,6 +921,7 @@ final class ActivityManagerConstants extends ContentObserver {
     public static int BINDER_HEAVY_HITTER_AUTO_SAMPLER_BATCHSIZE;
     public static float BINDER_HEAVY_HITTER_AUTO_SAMPLER_THRESHOLD;
     public static boolean PROACTIVE_KILLS_ENABLED = DEFAULT_PROACTIVE_KILLS_ENABLED;
+    public static float LOW_SWAP_THRESHOLD_PERCENT = DEFAULT_LOW_SWAP_THRESHOLD_PERCENT;
 
     private final OnPropertiesChangedListener mOnDeviceConfigChangedListener =
             new OnPropertiesChangedListener() {
@@ -1051,6 +1061,9 @@ final class ActivityManagerConstants extends ContentObserver {
                             case KEY_PROACTIVE_KILLS_ENABLED:
                                 updateProactiveKillsEnabled();
                                 break;
+                            case KEY_LOW_SWAP_THRESHOLD_PERCENT:
+                                updateLowSwapThresholdPercent();
+                                break;
                             default:
                                 break;
                         }
@@ -1678,6 +1691,13 @@ final class ActivityManagerConstants extends ContentObserver {
                 DEFAULT_PROACTIVE_KILLS_ENABLED);
     }
 
+    private void updateLowSwapThresholdPercent() {
+        LOW_SWAP_THRESHOLD_PERCENT = DeviceConfig.getFloat(
+                DeviceConfig.NAMESPACE_ACTIVITY_MANAGER,
+                KEY_LOW_SWAP_THRESHOLD_PERCENT,
+                DEFAULT_LOW_SWAP_THRESHOLD_PERCENT);
+    }
+
     private void updateMinAssocLogDuration() {
         MIN_ASSOC_LOG_DURATION = DeviceConfig.getLong(
                 DeviceConfig.NAMESPACE_ACTIVITY_MANAGER, KEY_MIN_ASSOC_LOG_DURATION,
@@ -1880,6 +1900,8 @@ final class ActivityManagerConstants extends ContentObserver {
         pw.print("="); pw.println(mMaxServiceConnectionsPerProcess);
         pw.print("  "); pw.print(KEY_PROACTIVE_KILLS_ENABLED);
         pw.print("="); pw.println(PROACTIVE_KILLS_ENABLED);
+        pw.print("  "); pw.print(KEY_LOW_SWAP_THRESHOLD_PERCENT);
+        pw.print("="); pw.println(LOW_SWAP_THRESHOLD_PERCENT);
 
         pw.println();
         if (mOverrideMaxCachedProcesses >= 0) {
diff --git a/services/core/java/com/android/server/am/OomAdjuster.java b/services/core/java/com/android/server/am/OomAdjuster.java
index 96e6ace5c56f2..eb2b7d493251e 100644
--- a/services/core/java/com/android/server/am/OomAdjuster.java
+++ b/services/core/java/com/android/server/am/OomAdjuster.java
@@ -1149,7 +1149,7 @@ public class OomAdjuster {
         int numTrimming = 0;
 
         boolean proactiveKillsEnabled = mConstants.PROACTIVE_KILLS_ENABLED;
-        double lowSwapThresholdPercent = 0.10;  // TODO: Configure from phenotype
+        double lowSwapThresholdPercent = mConstants.LOW_SWAP_THRESHOLD_PERCENT;
         double freeSwapPercent =  proactiveKillsEnabled ? getFreeSwapPercent() : 1.00;
         ProcessRecord lruCachedApp = null;