Don't assume kernel tick is 100Hz (914fc2a0) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/os/KernelCpuSpeedReader.java

+10 −3

Original line number	Diff line number	Diff line
		@@ -16,8 +16,11 @@
		package com.android.internal.os;

		import android.text.TextUtils;
		import android.system.OsConstants;
		import android.util.Slog;

		import libcore.io.Libcore;

		import java.io.BufferedReader;
		import java.io.FileReader;
		import java.io.IOException;
		@@ -29,7 +32,7 @@ import java.util.Arrays;
		*
		* freq time
		*
		* where time is measured in 1/100 seconds.
		* where time is measured in jiffies.
		*/
		public class KernelCpuSpeedReader {
		private static final String TAG = "KernelCpuSpeedReader";
		@@ -38,6 +41,9 @@ public class KernelCpuSpeedReader {
		private final long[] mLastSpeedTimes;
		private final long[] mDeltaSpeedTimes;

		// How long a CPU jiffy is in milliseconds.
		private final long mJiffyMillis;

		/**
		* @param cpuNumber The cpu (cpu0, cpu1, etc) whose state to read.
		*/
		@@ -46,6 +52,8 @@ public class KernelCpuSpeedReader {
		cpuNumber);
		mLastSpeedTimes = new long[numSpeedSteps];
		mDeltaSpeedTimes = new long[numSpeedSteps];
		long jiffyHz = Libcore.os.sysconf(OsConstants._SC_CLK_TCK);
		mJiffyMillis = 1000/jiffyHz;
		}

		/**
		@@ -62,8 +70,7 @@ public class KernelCpuSpeedReader {
		splitter.setString(line);
		Long.parseLong(splitter.next());

		// The proc file reports time in 1/100 sec, so convert to milliseconds.
		long time = Long.parseLong(splitter.next()) * 10;
		long time = Long.parseLong(splitter.next()) * mJiffyMillis;
		if (time < mLastSpeedTimes[speedIndex]) {
		// The stats reset when the cpu hotplugged. That means that the time
		// we read is offset from 0, so the time is the delta.

+2 −2

Original line number	Diff line number	Diff line
		@@ -67,10 +67,10 @@ public class ProcessCpuTracker {
		static final int PROCESS_STAT_UTIME = 2;
		static final int PROCESS_STAT_STIME = 3;

		/** Stores user time and system time in 100ths of a second. */
		/** Stores user time and system time in jiffies. */
		private final long[] mProcessStatsData = new long[4];

		/** Stores user time and system time in 100ths of a second. Used for
		/** Stores user time and system time in jiffies. Used for
		* public API to retrieve CPU use for a process. Must lock while in use. */
		private final long[] mSinglePidStatsData = new long[4];