/* * $Id: pa_cpuload.c,v 1.1.2.14 2004/01/08 22:01:12 rossbencina Exp $ * Portable Audio I/O Library CPU Load measurement functions * Portable CPU load measurement facility. * * Based on the Open Source API proposed by Ross Bencina * Copyright (c) 2002 Ross Bencina * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files * (the "Software"), to deal in the Software without restriction, * including without limitation the rights to use, copy, modify, merge, * publish, distribute, sublicense, and/or sell copies of the Software, * and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * Any person wishing to distribute modifications to the Software is * requested to send the modifications to the original developer so that * they can be incorporated into the canonical version. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /** @file @brief Functions to assist in measuring the CPU utilization of a callback stream. Used to implement the Pa_GetStreamCpuLoad() function. @todo Dynamically calculate the coefficients used to smooth the CPU Load Measurements over time to provide a uniform characterisation of CPU Load independent of rate at which PaUtil_BeginCpuLoadMeasurement / PaUtil_EndCpuLoadMeasurement are called. */ #include "pa_cpuload.h" #include #include "pa_util.h" /* for PaUtil_GetTime() */ void PaUtil_InitializeCpuLoadMeasurer( PaUtilCpuLoadMeasurer* measurer, double sampleRate ) { assert( sampleRate > 0 ); measurer->samplingPeriod = 1. / sampleRate; measurer->averageLoad = 0.; } void PaUtil_ResetCpuLoadMeasurer( PaUtilCpuLoadMeasurer* measurer ) { measurer->averageLoad = 0.; } void PaUtil_BeginCpuLoadMeasurement( PaUtilCpuLoadMeasurer* measurer ) { measurer->measurementStartTime = PaUtil_GetTime(); } void PaUtil_EndCpuLoadMeasurement( PaUtilCpuLoadMeasurer* measurer, unsigned long framesProcessed ) { double measurementEndTime, secondsFor100Percent, measuredLoad; if( framesProcessed > 0 ){ measurementEndTime = PaUtil_GetTime(); assert( framesProcessed > 0 ); secondsFor100Percent = framesProcessed * measurer->samplingPeriod; measuredLoad = (measurementEndTime - measurer->measurementStartTime) / secondsFor100Percent; /* Low pass filter the calculated CPU load to reduce jitter using a simple IIR low pass filter. */ /** FIXME @todo these coefficients shouldn't be hardwired */ #define LOWPASS_COEFFICIENT_0 (0.9) #define LOWPASS_COEFFICIENT_1 (0.99999 - LOWPASS_COEFFICIENT_0) measurer->averageLoad = (LOWPASS_COEFFICIENT_0 * measurer->averageLoad) + (LOWPASS_COEFFICIENT_1 * measuredLoad); } } double PaUtil_GetCpuLoad( PaUtilCpuLoadMeasurer* measurer ) { return measurer->averageLoad; }