hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling
Class FirstFitScheduler

java.lang.Object
  hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling.Scheduler
      hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling.FirstFitScheduler

Direct Known Subclasses:

NonQueueingScheduler, RandomScheduler, RoundRobinScheduler, SmallestFirstScheduler

public class FirstFitScheduler
extends Scheduler

This class implements one of the simplest VM schedulers: it places every VM on the first PM that would actually accept it. The scheduler does not rearrange the queue, thus if there would be some queued entities that would be possible to schedule this scheduler just ignores them until they reach the head of the queue.

Author:

"Gabor Kecskemeti, Laboratory of Parallel and Distributed Systems, MTA SZTAKI (c) 2012"

Nested Class Summary

Nested classes/interfaces inherited from class hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling.Scheduler

Scheduler.QueueingEvent

Field Summary

private PMIterator	it the iterator of the running PMs allowing to easily traverse the PM set in a predefined order.
(package private) PhysicalMachine.ResourceAllocation	raBiggestNotSuitable the largest allocation that was possible to collect from all running PMs in the infrastructure.
(package private) PhysicalMachine.ResourceAllocation[]	ras The set of resource allocations made for the current VM request (this is important for multi VM requests)

Fields inherited from class hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling.Scheduler

freeCapacity, parent, pmComparator, pmstateChanged, publicTQ, queue

Constructor Summary

FirstFitScheduler(IaaSService parent)
the constructor of the scheduler that passes on the parent IaaS service and initiates the basic PM iterator for this scheduler which will

Method Summary

protected PMIterator	getPMIterator() Resets the iterator then offers it to the caller
protected PMIterator	instantiateIterator() Allows the customization of the PM iterator by subclasses.
protected ConstantConstraints	scheduleQueued() The actual first fit scheduling implementation.

Methods inherited from class hu.mta.sztaki.lpds.cloud.simulator.iaas.vmscheduling.Scheduler

dropVMrequest, getQueuedVMs, getQueueLength, getTotalQueued, manageQueueRemoval, manageQueueRemoval, scheduleVMrequest, subscribeQueueingEvents, unsubscribeQueueingEvents

Methods inherited from class java.lang.Object

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

Field Detail

ras

PhysicalMachine.ResourceAllocation[] ras

The set of resource allocations made for the current VM request (this is important for multi VM requests)

raBiggestNotSuitable

PhysicalMachine.ResourceAllocation raBiggestNotSuitable

the largest allocation that was possible to collect from all running PMs in the infrastructure. this is important to determine the amount of resources that need to become free before the scheduler would be able to place the head of the queue to any of the PMs in the infrastructure.

it

private final PMIterator it

the iterator of the running PMs allowing to easily traverse the PM set in a predefined order. The iterator plays a crucial role in this implementation as several FirstFit derivatives only differ in their handling of the PMs.

Constructor Detail

FirstFitScheduler

public FirstFitScheduler(IaaSService parent)

the constructor of the scheduler that passes on the parent IaaS service and initiates the basic PM iterator for this scheduler which will

Parameters:

parent -

Method Detail

instantiateIterator

protected PMIterator instantiateIterator()

Allows the customization of the PM iterator by subclasses. This function is not intended to be used by anything else but the constructor of this class.

Returns:

the desired PM iterator to be used for traversing the PMs while doing the scheduling

getPMIterator

protected PMIterator getPMIterator()

Resets the iterator then offers it to the caller

Returns:

the PMIterator that is ready to be used during the scheduling process

scheduleQueued

protected ConstantConstraints scheduleQueued()

The actual first fit scheduling implementation. This implementation supports requests with multiple VMs. It assumes that users want to deploy all VMs or nothing so it waits until all VMs could be deployed at once.

Specified by:

scheduleQueued in class Scheduler

Returns:

the amount of free resources that the IaaS service needs to offer before this scheduler could actually proceed with its next VM placement.