Bug fix of Tx PER when packet count is low

Use default Tx PER when packet count is low because PER estimation is
unreliable with low Tx packet count.

Bug: 159866355
Test: atest com.android.server.wifi
Change-Id: Ide48ab41420c9c907fc50a32aef10b47360209d4

3 files changed, 8 insertions, 6 deletions

diff --git a/service/java/com/android/server/wifi/DeviceConfigFacade.java b/service/java/com/android/server/wifi/DeviceConfigFacade.java
index 0e43a0891..0b707701f 100644
--- a/service/java/com/android/server/wifi/DeviceConfigFacade.java
+++ b/service/java/com/android/server/wifi/DeviceConfigFacade.java
@@ -66,7 +66,7 @@ public class DeviceConfigFacade {
     // Denominator part of default threshold of L2 throughput over L3 throughput ratio
     public static final int DEFAULT_TPUT_SUFFICIENT_RATIO_THR_DEN = 1;
     // Default threshold of Tx packet per second
-    public static final int DEFAULT_TX_PACKET_PER_SECOND_THR = 1;
+    public static final int DEFAULT_TX_PACKET_PER_SECOND_THR = 2;
     // Default threshold of Rx packet per second
     public static final int DEFAULT_RX_PACKET_PER_SECOND_THR = 1;
     // Default high threshold values for various connection/disconnection cases
diff --git a/service/java/com/android/server/wifi/WifiDataStall.java b/service/java/com/android/server/wifi/WifiDataStall.java
index 7ae577900..ebc184773 100644
--- a/service/java/com/android/server/wifi/WifiDataStall.java
+++ b/service/java/com/android/server/wifi/WifiDataStall.java
@@ -296,7 +296,8 @@ public class WifiDataStall {
         }
         logd(" ccaLevel = " + ccaLevel);
 
-        int txPer = updateTxPer(txSuccessDelta, txRetriesDelta, isSameBssidAndFreq);
+        int txPer = updateTxPer(txSuccessDelta, txRetriesDelta, isSameBssidAndFreq,
+                isTxTrafficHigh);
 
         boolean isTxTputLow = false;
         boolean isRxTputLow = false;
@@ -397,12 +398,13 @@ public class WifiDataStall {
         return WifiIsUnusableEvent.TYPE_UNKNOWN;
     }
 
-    private int updateTxPer(long txSuccessDelta, long txRetriesDelta, boolean isSameBssidAndFreq) {
+    private int updateTxPer(long txSuccessDelta, long txRetriesDelta, boolean isSameBssidAndFreq,
+            boolean isTxTrafficHigh) {
         if (!isSameBssidAndFreq) {
             return DEFAULT_TX_PACKET_ERROR_RATE;
         }
         long txAttempts = txSuccessDelta + txRetriesDelta;
-        if (txAttempts <= 0) {
+        if (txAttempts <= 0 || !isTxTrafficHigh) {
             return DEFAULT_TX_PACKET_ERROR_RATE;
         }
         return (int) (txRetriesDelta * 100 / txAttempts);
diff --git a/tests/wifitests/src/com/android/server/wifi/WifiDataStallTest.java b/tests/wifitests/src/com/android/server/wifi/WifiDataStallTest.java
index 61979f1e8..4ed08a3d1 100644
--- a/tests/wifitests/src/com/android/server/wifi/WifiDataStallTest.java
+++ b/tests/wifitests/src/com/android/server/wifi/WifiDataStallTest.java
@@ -342,7 +342,7 @@ public class WifiDataStallTest extends WifiBaseTest {
         assertEquals(WifiIsUnusableEvent.TYPE_UNKNOWN, mWifiDataStall
                 .checkDataStallAndThroughputSufficiency(mOldLlStats, mNewLlStats, mWifiInfo));
         assertEquals(true, mWifiDataStall.isThroughputSufficient());
-        assertEquals(4804, mWifiDataStall.getTxThroughputKbps());
+        assertEquals(9128, mWifiDataStall.getTxThroughputKbps());
         assertEquals(-1, mWifiDataStall.getRxThroughputKbps());
         verify(mWifiMetrics, never()).logWifiIsUnusableEvent(anyInt());
     }
@@ -400,7 +400,7 @@ public class WifiDataStallTest extends WifiBaseTest {
         assertEquals(WifiIsUnusableEvent.TYPE_UNKNOWN, mWifiDataStall
                 .checkDataStallAndThroughputSufficiency(mOldLlStats, mNewLlStats, mWifiInfo));
         assertEquals(true, mWifiDataStall.isThroughputSufficient());
-        assertEquals(4707, mWifiDataStall.getTxThroughputKbps());
+        assertEquals(8943, mWifiDataStall.getTxThroughputKbps());
         assertEquals(9414, mWifiDataStall.getRxThroughputKbps());
     }