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Commit dc3a7835 authored by Dmitri Plotnikov's avatar Dmitri Plotnikov
Browse files

Address race condition in procstate time tracking 

The issue occurs when the application proc state changes
rapidly, e.g. from FOREGROUND to BACKGROUND to CACHED.
The original code would sometimes attribute the time slice
to the wrong proc state.

Bug: 192550308
Test: (on cuttlefish) atest --rerun-until-failure 300 FrameworksCoreTests:com.android.internal.os.BstatsCpuTimesValidationTest -- --abi x86_64

Change-Id: Ic22bbfa3aae701014fc016ec9e2d32b1c528d462
parent fb0faec3

core/java/android/os/BatteryStats.java

+3 −4
Original line number Diff line number Diff line
@@ -16,7 +16,6 @@ 


package android.os;



import static android.app.ActivityManager.PROCESS_STATE_BOUND_TOP;

import static android.os.BatteryStatsManager.NUM_WIFI_STATES;

import static android.os.BatteryStatsManager.NUM_WIFI_SUPPL_STATES;
@@ -903,9 +902,9 @@ public abstract class BatteryStats implements Parcelable { 
         * is not attributed to any non-critical process states.

         */

        public static final int[] CRITICAL_PROC_STATES = {

                PROCESS_STATE_TOP,

                PROCESS_STATE_BOUND_TOP, PROCESS_STATE_FOREGROUND_SERVICE,

                PROCESS_STATE_FOREGROUND

                Uid.PROCESS_STATE_TOP,

                Uid.PROCESS_STATE_FOREGROUND_SERVICE,

                Uid.PROCESS_STATE_FOREGROUND

        };



        public abstract long getProcessStateTime(int state, long elapsedRealtimeUs, int which);

core/tests/coretests/src/com/android/internal/os/BstatsCpuTimesValidationTest.java

+9 −3
Original line number Diff line number Diff line
@@ -584,7 +584,7 @@ public class BstatsCpuTimesValidationTest { 
                actualCpuTimeMs += cpuTimesMs[i];

            }

            assertApproximateValue("Incorrect total cpu time, " + msgCpuTimes,

                    2 * WORK_DURATION_MS, actualCpuTimeMs);

                    WORK_DURATION_MS, actualCpuTimeMs);



            batteryOffScreenOn();

        } finally {
@@ -656,8 +656,14 @@ public class BstatsCpuTimesValidationTest { 
        }

    }



    private void assertApproximateValue(String errorPrefix, long expectedValue, long actualValue) {

        assertValueRange(errorPrefix, actualValue, expectedValue * 0.5, expectedValue * 1.5);

    private void assertApproximateValue(String errorPrefix, long expectedValueMs,

            long actualValueMs) {

        // Allow the actual value to be 1 second smaller than the expected.

        // Also allow it to be up to 5 seconds larger, to accommodate the arbitrary

        // latency introduced by BatteryExternalStatsWorker.scheduleReadProcStateCpuTimes

        assertValueRange(errorPrefix, actualValueMs,

                expectedValueMs - 1000,

                expectedValueMs + 5000);

    }



    private void assertValueRange(String errorPrefix,