org.btrplace.scheduler.choco.view.CNetwork Maven / Gradle / Ivy
/*
* Copyright 2021 The BtrPlace Authors. All rights reserved.
* Use of this source code is governed by a LGPL-style
* license that can be found in the LICENSE.txt file.
*/
package org.btrplace.scheduler.choco.view;
import org.btrplace.model.Attributes;
import org.btrplace.model.Model;
import org.btrplace.model.Node;
import org.btrplace.model.VM;
import org.btrplace.model.view.network.Link;
import org.btrplace.model.view.network.Network;
import org.btrplace.model.view.network.Routing.LinkDirection;
import org.btrplace.model.view.network.Switch;
import org.btrplace.scheduler.SchedulerException;
import org.btrplace.scheduler.SchedulerModelingException;
import org.btrplace.scheduler.choco.Parameters;
import org.btrplace.scheduler.choco.ReconfigurationProblem;
import org.btrplace.scheduler.choco.transition.RelocatableVM;
import org.btrplace.scheduler.choco.transition.VMTransition;
import org.chocosolver.solver.Cause;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.Task;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* The solver part of the network view.
* Define the maximal bandwidth allocatable for each migration according to the capacity
* of the network elements on each migration path. Then, establish the relation between the
* migrations duration and their allocated bandwidth based on specific VMs attributes related
* to VM memory activity.
*
* @author Vincent Kherbache
*/
public class CNetwork implements ChocoView {
/**
* The view identifier.
*/
public static final String VIEW_ID = "NetworkView";
private final Network net;
private org.chocosolver.solver.Model csp;
private Model source;
/**
* Make a new network view.
*
* @param n the network view we rely on
*/
public CNetwork(Network n) throws SchedulerException {
net = n;
}
@Override
public boolean inject(Parameters ps, ReconfigurationProblem rp) throws SchedulerException {
csp = rp.getModel();
source = rp.getSourceModel();
return true;
}
@Override
public String getIdentifier() {
return net.getIdentifier();
}
@Override
public boolean beforeSolve(ReconfigurationProblem rp) throws SchedulerException {
Model mo = rp.getSourceModel();
Attributes attrs = mo.getAttributes();
// Pre-compute duration and bandwidth for each VM migration
for (VMTransition migration : rp.getVMActions()) {
if (!(migration instanceof RelocatableVM)) {
continue;
}
// Get vars from migration
VM vm = migration.getVM();
IntVar bandwidth = ((RelocatableVM) migration).getBandwidth();
IntVar duration = migration.getDuration();
Node src = rp.getSourceModel().getMapping().getVMLocation(vm);
// Try to get the destination node
Node dst;
if (!migration.getDSlice().getHoster().isInstantiated()) {
throw new SchedulerModelingException(null, "Destination node for VM '" + vm + "' should be known !");
}
if (!mo.getAttributes().isSet(vm, "memUsed")) {
throw new SchedulerModelingException(null, "Unable to retrieve 'memUsed' attribute for the vm '" + vm + "'");
}
dst = rp.getNode(migration.getDSlice().getHoster().getValue());
if (src.equals(dst)) {
try {
((RelocatableVM) migration).getBandwidth().instantiateTo(0, Cause.Null);
continue;
} catch (ContradictionException e) {
rp.getLogger().debug("Contradiction exception when trying to instantiate bandwidth and " +
" duration variables for " + vm + " migration", e);
return false;
}
}
// Get attribute vars
int memUsed = attrs.get(vm, "memUsed", -1);
// Get VM memory activity attributes if defined, otherwise set an idle workload on the VM
double hotDirtySize = attrs.get(vm, "hotDirtySize", 5.0);// Minimal observed value on idle VM
double hotDirtyDuration = attrs.get(vm, "hotDirtyDuration", 2.0); // Minimal observed value on idle VM
double coldDirtyRate = attrs.get(vm, "coldDirtyRate", 0.0);
// Get the maximal bandwidth available on the migration path
int maxBW = net.getRouting().getMaxBW(src, dst);
// Compute the duration related to each enumerated bandwidth
double durationMin;
double durationColdPages;
double durationHotPages;
double durationTotal;
// Cheat a bit, real is less than theoretical (8->9)
double bandwidthOctet = maxBW / 9.0;
// Estimate the duration for the current bandwidth
durationMin = memUsed / bandwidthOctet;
if (durationMin > hotDirtyDuration) {
durationColdPages = (hotDirtySize + (durationMin - hotDirtyDuration) * coldDirtyRate) /
(bandwidthOctet - coldDirtyRate);
durationHotPages = (hotDirtySize / bandwidthOctet * ((hotDirtySize / hotDirtyDuration) /
(bandwidthOctet - (hotDirtySize / hotDirtyDuration))));
durationTotal = durationMin + durationColdPages + durationHotPages;
} else {
durationTotal = durationMin + (((hotDirtySize / hotDirtyDuration) * durationMin) /
(bandwidthOctet - (hotDirtySize / hotDirtyDuration)));
}
// Instantiate the computed bandwidth and duration
try {
//prevent from a 0 duration when the memory usage is very low
int dd = (int) Math.max(1, Math.round(durationTotal));
duration.instantiateTo(dd, Cause.Null);
bandwidth.instantiateTo(maxBW, Cause.Null);
} catch (ContradictionException e) {
rp.getLogger().debug("Contradiction exception when trying to instantiate bandwidth and " +
" duration variables for " + vm + " migration: ", e);
return false;
}
}
// Add links and switches constraints
addLinkConstraints(rp);
addSwitchConstraints(rp);
return true;
}
/**
* Add the cumulative constraints for each link.
*
* Full-duplex links are considered, two cumulative constraints are defined per link by looking at
* the migration direction for each link on the migration path.
*
* @param rp the reconfiguration problem
*/
private void addLinkConstraints(ReconfigurationProblem rp) {
// Links limitation
List tasksListUp = new ArrayList<>();
List tasksListDown = new ArrayList<>();
List heightsListUp = new ArrayList<>();
List heightsListDown = new ArrayList<>();
for (Link l : net.getLinks()) {
for (VM vm : rp.getVMs()) {
VMTransition a = rp.getVMAction(vm);
if (a instanceof RelocatableVM
&& !a.getDSlice().getHoster().isInstantiatedTo(a.getCSlice().getHoster().getValue())) {
Node src = source.getMapping().getVMLocation(vm);
Node dst = rp.getNode(a.getDSlice().getHoster().getValue());
List path = net.getRouting().getPath(src, dst);
// Check first if the link is on migration path
if (path.contains(l)) {
// Get link direction
LinkDirection linkDirection = net.getRouting().getLinkDirection(src, dst, l);
// UpLink
if (linkDirection == LinkDirection.UPLINK) {
tasksListUp.add(((RelocatableVM) a).getMigrationTask());
heightsListUp.add(((RelocatableVM) a).getBandwidth());
}
// DownLink
else {
tasksListDown.add(((RelocatableVM) a).getMigrationTask());
heightsListDown.add(((RelocatableVM) a).getBandwidth());
}
}
}
}
if (!tasksListUp.isEmpty()) {
// Post the cumulative constraint for the current UpLink
csp.post(csp.cumulative(
tasksListUp.toArray(new Task[tasksListUp.size()]),
heightsListUp.toArray(new IntVar[heightsListUp.size()]),
csp.intVar(l.getCapacity()),
true
));
tasksListUp.clear();
heightsListUp.clear();
}
if (!tasksListDown.isEmpty()) {
// Post the cumulative constraint for the current DownLink
csp.post(csp.cumulative(
tasksListDown.toArray(new Task[tasksListDown.size()]),
heightsListDown.toArray(new IntVar[heightsListDown.size()]),
csp.intVar(l.getCapacity()),
true
));
tasksListDown.clear();
heightsListDown.clear();
}
}
}
/**
* Add the cumulative constraints for each blocking switch (having limited capacity)
*
* @param rp the reconfiguration problem
*/
private void addSwitchConstraints(ReconfigurationProblem rp) {
// Switches capacity limitation
List tasksList = new ArrayList<>();
List heightsList = new ArrayList<>();
for(Switch sw : net.getSwitches()) {
// Only if the capacity is limited
if (sw.getCapacity() != Integer.MAX_VALUE) {
for (VM vm : rp.getVMs()) {
VMTransition a = rp.getVMAction(vm);
if (a != null && a instanceof RelocatableVM) {
if (a.getDSlice().getHoster().isInstantiated()) {
if (a.getCSlice().getHoster().getValue() != a.getDSlice().getHoster().getValue()) {
Node src = source.getMapping().getVMLocation(vm);
Node dst = rp.getNode(a.getDSlice().getHoster().getValue());
if (!Collections.disjoint(net.getConnectedLinks(sw), net.getRouting().getPath(src, dst))) {
tasksList.add(new Task(a.getStart(), a.getDuration(), a.getEnd()));
heightsList.add(((RelocatableVM) a).getBandwidth());
}
}
}
}
}
if (!tasksList.isEmpty()) {
// Post the cumulative constraint for the current switch
csp.post(csp.cumulative(
tasksList.toArray(new Task[tasksList.size()]),
heightsList.toArray(new IntVar[heightsList.size()]),
csp.intVar(sw.getCapacity()),
true
));
tasksList.clear();
heightsList.clear();
}
}
}
}
}
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