/*
* Title: CloudSim Toolkit
* Description: CloudSim (Cloud Simulation) Toolkit for Modeling and Simulation of Clouds
* Licence: GPL - http://www.gnu.org/copyleft/gpl.html
*
* Copyright (c) 2009-2012, The University of Melbourne, Australia
*/
package org.cloudbus.cloudsim.power;
import java.util.List;
import org.cloudbus.cloudsim.Host;
import org.cloudbus.cloudsim.Log;
import org.cloudbus.cloudsim.Vm;
import org.cloudbus.cloudsim.util.MathUtil;
/**
* A VM allocation policy that uses Median Absolute Deviation (MAD) to compute
* a dynamic threshold in order to detect host over utilization.
*
* <br/>If you are using any algorithms, policies or workload included in the power package please cite
* the following paper:<br/>
*
* <ul>
* <li><a href="http://dx.doi.org/10.1002/cpe.1867">Anton Beloglazov, and Rajkumar Buyya, "Optimal Online Deterministic Algorithms and Adaptive
* Heuristics for Energy and Performance Efficient Dynamic Consolidation of Virtual Machines in
* Cloud Data Centers", Concurrency and Computation: Practice and Experience (CCPE), Volume 24,
* Issue 13, Pages: 1397-1420, John Wiley & Sons, Ltd, New York, USA, 2012</a>
* </ul>
*
* @author Anton Beloglazov
* @since CloudSim Toolkit 3.0
*/
public class PowerVmAllocationPolicyMigrationMedianAbsoluteDeviation extends
PowerVmAllocationPolicyMigrationAbstract {
/** The safety parameter in percentage (at scale from 0 to 1).
* It is a tuning parameter used by the allocation policy to define
* when a host is overloaded. The overload detection is based
* on a dynamic defined host utilization threshold. This threshold
* is computed based on the host's usage history Median absolute deviation
* (MAD, that is similar to the Standard Deviation).
* This safety parameter is used to increase or decrease the MAD value
* when computing the utilization threshold.
* As the safety parameter increases, the threshold decreases,
* what may lead to less SLA violations. So, as higher is that parameter,
* safer the algorithm will be when defining a host as overloaded.
* For instance, considering a safety parameter of 1.5 (150%),
* a host's resource usage mean is 0.5 (50%)
* and a MAD of 0.2 (thus, the usage may vary from 0.3 to 0.7).
* To compute the usage threshold, the MAD is increased by 50%, being equals to 0.3.
* Finally, the threshold will be 1 - 0.3 = 0.7.
* Thus, only when the host utilization threshold exceeds 70%,
* the host is considered overloaded.
* Here, more safe or less safe doesn't means a more accurate or less accurate
* overload detection. Safer means the algorithm will use a lower host
* utilization threshold that may lead to lower SLA violations but higher
* resource wastage. Thus this parameter has to be tuned in order to
* trade-off between SLA violation and resource wastage.
*/
private double safetyParameter = 0;
/** The fallback VM allocation policy to be used when
* the MAD over utilization host detection doesn't have
* data to be computed. */
private PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy;
/**
* Instantiates a new PowerVmAllocationPolicyMigrationMedianAbsoluteDeviation.
*
* @param hostList the host list
* @param vmSelectionPolicy the vm selection policy
* @param safetyParameter the safety parameter
* @param utilizationThreshold the utilization threshold
*/
public PowerVmAllocationPolicyMigrationMedianAbsoluteDeviation(
List<? extends Host> hostList,
PowerVmSelectionPolicy vmSelectionPolicy,
double safetyParameter,
PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy,
double utilizationThreshold) {
super(hostList, vmSelectionPolicy);
setSafetyParameter(safetyParameter);
setFallbackVmAllocationPolicy(fallbackVmAllocationPolicy);
}
/**
* Instantiates a new PowerVmAllocationPolicyMigrationMedianAbsoluteDeviation.
*
* @param hostList the host list
* @param vmSelectionPolicy the vm selection policy
* @param safetyParameter the safety parameter
*/
public PowerVmAllocationPolicyMigrationMedianAbsoluteDeviation(
List<? extends Host> hostList,
PowerVmSelectionPolicy vmSelectionPolicy,
double safetyParameter,
PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy) {
super(hostList, vmSelectionPolicy);
setSafetyParameter(safetyParameter);
setFallbackVmAllocationPolicy(fallbackVmAllocationPolicy);
}
/**
* Checks if a host is over utilized.
*
* @param host the host
* @return true, if the host is over utilized; false otherwise
*/
@Override
protected boolean isHostOverUtilized(PowerHost host) {
PowerHostUtilizationHistory _host = (PowerHostUtilizationHistory) host;
double upperThreshold = 0;
try {
upperThreshold = 1 - getSafetyParameter() * getHostUtilizationMad(_host);
} catch (IllegalArgumentException e) {
return getFallbackVmAllocationPolicy().isHostOverUtilized(host);
}
addHistoryEntry(host, upperThreshold);
double totalRequestedMips = 0;
for (Vm vm : host.getVmList()) {
totalRequestedMips += vm.getCurrentRequestedTotalMips();
}
double utilization = totalRequestedMips / host.getTotalMips();
return utilization > upperThreshold;
}
/**
* Gets the host utilization MAD.
*
* @param host the host
* @return the host utilization MAD
*/
protected double getHostUtilizationMad(PowerHostUtilizationHistory host) throws IllegalArgumentException {
double[] data = host.getUtilizationHistory();
if (MathUtil.countNonZeroBeginning(data) >= 12) { // 12 has been suggested as a safe value
return MathUtil.mad(data);
}
throw new IllegalArgumentException();
}
/**
* Sets the safety parameter.
*
* @param safetyParameter the new safety parameter
* @todo It should raise an InvalidArgumentException instead of calling System.exit(0)
*/
protected void setSafetyParameter(double safetyParameter) {
if (safetyParameter < 0) {
Log.printConcatLine("The safety parameter cannot be less than zero. The passed value is: ",
safetyParameter);
System.exit(0);
}
this.safetyParameter = safetyParameter;
}
/**
* Gets the safety parameter.
*
* @return the safety parameter
*/
protected double getSafetyParameter() {
return safetyParameter;
}
/**
* Sets the fallback vm allocation policy.
*
* @param fallbackVmAllocationPolicy the new fallback vm allocation policy
*/
public void setFallbackVmAllocationPolicy(
PowerVmAllocationPolicyMigrationAbstract fallbackVmAllocationPolicy) {
this.fallbackVmAllocationPolicy = fallbackVmAllocationPolicy;
}
/**
* Gets the fallback vm allocation policy.
*
* @return the fallback vm allocation policy
*/
public PowerVmAllocationPolicyMigrationAbstract getFallbackVmAllocationPolicy() {
return fallbackVmAllocationPolicy;
}
}