com.serenegiant.utils

Class CpuMonitor

java.lang.Object

com.serenegiant.utils.CpuMonitor

public final class CpuMonitor
extends java.lang.Object

Modified 2016 t_saki@serenegiant.com Simple CPU monitor. The caller creates a CpuMonitor object which can then be used via sampleCpuUtilization() to collect the percentual use of the cumulative CPU capacity for all CPUs running at their nominal frequency. 3 values are generated: (1) getCpuCurrent() returns the use since the last sampleCpuUtilization(), (2) getCpuAvg3() returns the use since 3 prior calls, and (3) getCpuAvgAll() returns the use over all SAMPLE_SAVE_NUMBER calls.

CPUs in Android are often "offline", and while this of course means 0 Hz as current frequency, in this state we cannot even get their nominal frequency. We therefore tread carefully, and allow any CPU to be missing. Missing CPUs are assumed to have the same nominal frequency as any close lower-numbered CPU, but as soon as it is online, we'll get their proper frequency and remember it. (Since CPU 0 in practice always seem to be online, this unidirectional frequency inheritance should be no problem in practice.)

Caveats: o No provision made for zany "turbo" mode, common in the x86 world. o No provision made for ARM big.LITTLE; if CPU n can switch behind our back, we might get incorrect estimates. o This is not thread-safe. To call asynchronously, create different CpuMonitor objects.

If we can gather enough info to generate a sensible result, sampleCpuUtilization returns true. It is designed to never through an exception.

sampleCpuUtilization should not be called too often in its present form, since then deltas would be small and the percent values would fluctuate and be unreadable. If it is desirable to call it more often than say once per second, one would need to increase SAMPLE_SAVE_NUMBER and probably use Queue to avoid copying overhead.

Known problems: 1. Nexus 7 devices running Kitkat have a kernel which often output an incorrect 'idle' field in /proc/stat. The value is close to twice the correct value, and then returns to back to correct reading. Both when jumping up and back down we might create faulty CPU load readings.

Constructor Summary

Constructors

Constructor and Description
CpuMonitor()

Method Summary

Modifier and Type	Method and Description
int	getCpuAvg3()
int	getCpuAvgAll()
int	getCpuCurrent()
int	getTemp(int ix)
float	getTempAve()
int	getTempNum()
boolean	sampleCpuUtilization() Re-measure CPU use.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CpuMonitor

public CpuMonitor()

Method Detail

sampleCpuUtilization

public boolean sampleCpuUtilization()

Re-measure CPU use. Call this method at an interval of around 1/s. This method returns true on success. The fields cpuCurrent, cpuAvg3, and cpuAvgAll are updated on success, and represents: cpuCurrent: The CPU use since the last sampleCpuUtilization call. cpuAvg3: The average CPU over the last 3 calls. cpuAvgAll: The average CPU over the last SAMPLE_SAVE_NUMBER calls. CPU周辺の温度を取得するのが少し重いのでUIスレッドからは呼び出さないほうが良い

getCpuCurrent

public int getCpuCurrent()

getCpuAvg3

public int getCpuAvg3()

getCpuAvgAll

public int getCpuAvgAll()

getTempNum

public int getTempNum()

getTemp

public int getTemp(int ix)

getTempAve

public float getTempAve()