org.mmtk.plan.immix

Class Immix

java.lang.Object

org.mmtk.plan.Plan

org.mmtk.plan.Simple

org.mmtk.plan.StopTheWorld

org.mmtk.plan.immix.Immix

Direct Known Subclasses:

StickyImmix

public class Immix
extends StopTheWorld

This class implements the global state of an immix collector.

See the PLDI'08 paper by Blackburn and McKinley for a description of the algorithm: http://doi.acm.org/10.1145/1375581.1375586

All plans make a clear distinction between global and thread-local activities, and divides global and local state into separate class hierarchies. Global activities must be synchronized, whereas no synchronization is required for thread-local activities. There is a single instance of Plan (or the appropriate sub-class), and a 1:1 mapping of PlanLocal to "kernel threads" (aka CPUs or in Jikes RVM, Processors). Thus instance methods of PlanLocal allow fast, unsychronized access to functions such as allocation and collection.

The global instance defines and manages static resources (such as memory and virtual memory resources). This mapping of threads to instances is crucial to understanding the correctness and performance properties of MMTk plans.

Field Summary

Fields

Modifier and Type	Field and Description
boolean	collectWholeHeap will this collection collect the whole heap
static int	IMMIX
static ImmixSpace	immixSpace
Trace	immixTrace
protected boolean	lastGCWasDefrag
boolean	nextGCWholeHeap will the next collection collect the whole heap?
static int	SCAN_DEFRAG
static int	SCAN_IMMIX

Fields inherited from class org.mmtk.plan.StopTheWorld

postSanityPhase, preSanityPhase

Fields inherited from class org.mmtk.plan.Simple

CLOSURE, collection, collectionAttempt, COMPLETE, completeClosurePhase, FINALIZABLE, finishPhase, FORWARD, FORWARD_FINALIZABLE, FORWARD_REFS, forwardPhase, INITIATE, initPhase, PHANTOM_REFS, POST_SANITY_PLACEHOLDER, PRE_SANITY_PLACEHOLDER, PREPARE, PREPARE_STACKS, prepareStacks, refTypeClosurePhase, RELEASE, rootClosurePhase, ROOTS, SANITY_BUILD_TABLE, SANITY_CHECK_TABLE, SANITY_COPY_ROOTS, SANITY_PREPARE, SANITY_RELEASE, SANITY_ROOTS, SANITY_SET_POSTGC, SANITY_SET_PREGC, sanityBuildPhase, sanityCheckPhase, SET_COLLECTION_KIND, SOFT_REFS, STACK_ROOTS, WEAK_REFS, WEAK_TRACK_REFS

Fields inherited from class org.mmtk.plan.Plan

ALLOC_CODE, ALLOC_COLD_CODE, ALLOC_DEFAULT, ALLOC_GCSPY, ALLOC_HOT_CODE, ALLOC_IMMORTAL, ALLOC_LARGE_CODE, ALLOC_LOS, ALLOC_NON_MOVING, ALLOC_NON_REFERENCE, ALLOC_PRIMITIVE_LOS, ALLOC_STACK, allocationSiteCount, ALLOCATORS, concurrentWorkers, controlCollectorContext, DEFAULT_MAX_NURSERY, DEFAULT_MIN_NURSERY, DEFAULT_SITE, defaultCollectorContext, emergencyCollection, GATHER_WRITE_BARRIER_STATS, GC_PREPARE, GC_PROPER, IMMORTAL, immortalSpace, insideHarness, internalTriggeredCollection, LARGE_CODE, largeCodeSpace, lastInternalTriggeredCollection, LOS, loSpace, MAX_NON_LOS_COPY_BYTES, MAX_NON_LOS_DEFAULT_ALLOC_BYTES, MAX_NON_LOS_NONMOVING_ALLOC_BYTES, META, metaDataSpace, NEEDS_LOG_BIT_IN_HEADER, NON_MOVING, NON_PARTICIPANT, nonMovingSpace, NOT_IN_GC, parallelWorkers, pretenureThreshold, SANITY, sanityChecker, sanitySpace, SCAN_BOOT_IMAGE, SMALL_CODE, smallCodeSpace, stacksPrepared, totalTime, USE_CODE_SPACE, userTriggeredCollection, VM_SPACE, vmSpace

Constructor Summary

Constructors

Constructor and Description
Immix() Constructor.

Method Summary

Modifier and Type	Method and Description
void	collectionPhase(short phaseId) Perform a (global) collection phase.
int	getCollectionReserve() Return the number of pages reserved for collection.
int	getPagesUsed() Return the number of pages reserved for use given the pending allocation.
boolean	lastCollectionWasExhaustive()
void	preCollectorSpawn() Prepares for spawning of collectors.
protected void	registerSpecializedMethods() Registers specialized methods.
boolean	willNeverMove(ObjectReference object) Can this object ever move.

Methods inherited from class org.mmtk.plan.StopTheWorld

processOptions

Methods inherited from class org.mmtk.plan.Simple

replacePhase, replacePlaceholderPhase, switchNurseryZeroingApproach

Methods inherited from class org.mmtk.plan.Plan

availableMemory, bootTimeWriteBarrier, collectionRequired, concurrentCollectionRequired, determineThreadCount, enableAllocation, enableCollection, forceFullHeapCollection, freeMemory, fullyBooted, gcInProgress, gcInProgressProper, getAllocationSite, getPagesAvail, getPagesReserved, getSpecializedScanClass, getTotalPages, handleUserCollectionRequest, harnessBegin, harnessEnd, insertPhaseAfter, isCurrentGCNursery, isEmergencyCollection, isInitialized, isInternalTriggeredCollection, isUserTriggeredCollection, lastCollectionFullHeap, loadObjectReference, logPoll, notifyExit, poll, printDetailedTiming, printPostStats, printPreStats, printUsedPages, reservedMemory, resetCollectionTrigger, sanityExpectedRC, sanityLinearScan, setBuildTimeGCByte, setGCStatus, spawnCollectorThreads, stacksPrepared, startGCspyServer, storeObjectReference, stressTestGCRequired, totalMemory, triggerInternalCollectionRequest, usedMemory

Methods inherited from class java.lang.Object

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

Field Detail

immixSpace

public static final ImmixSpace immixSpace

IMMIX

public static final int IMMIX

SCAN_IMMIX

public static final int SCAN_IMMIX

See Also:

Constant Field Values

SCAN_DEFRAG

public static final int SCAN_DEFRAG

See Also:

Constant Field Values

immixTrace

public final Trace immixTrace

nextGCWholeHeap

public boolean nextGCWholeHeap

will the next collection collect the whole heap?

collectWholeHeap

public boolean collectWholeHeap

will this collection collect the whole heap

lastGCWasDefrag

protected boolean lastGCWasDefrag

Constructor Detail

Immix

public Immix()

Constructor.

Method Detail

collectionPhase

public void collectionPhase(short phaseId)

Perform a (global) collection phase.

Overrides:

collectionPhase in class Simple

Parameters:

phaseId - The unique id of the phase to perform.

lastCollectionWasExhaustive

public boolean lastCollectionWasExhaustive()

Overrides:

lastCollectionWasExhaustive in class Plan

Returns:

Whether last GC was an exhaustive attempt to collect the heap. For many collectors this is the same as asking whether the last GC was a full heap collection.

getPagesUsed

public int getPagesUsed()

Return the number of pages reserved for use given the pending allocation. The superclass accounts for its spaces, we just augment this with the mark-sweep space's contribution.

Overrides:

getPagesUsed in class Plan

Returns:

The number of pages reserved given the pending allocation, excluding space reserved for copying.

getCollectionReserve

public int getCollectionReserve()

Return the number of pages reserved for collection.

Overrides:

getCollectionReserve in class Plan

Returns:

The number of pages reserved given the pending allocation, including space reserved for collection.

willNeverMove

public boolean willNeverMove(ObjectReference object)

Description copied from class: Plan

Can this object ever move. Used by the VM to make decisions about whether it needs to copy IO buffers etc.

Overrides:

willNeverMove in class Plan

Parameters:

object - The object in question

Returns:

true if it is not possible that the object will ever move.

registerSpecializedMethods

protected void registerSpecializedMethods()

Description copied from class: Plan

Registers specialized methods.

Overrides:

registerSpecializedMethods in class Plan

preCollectorSpawn

public void preCollectorSpawn()

Description copied from class: Plan

Prepares for spawning of collectors.

This is a good place to do initialization work that depends on options that are only known at runtime. Collectors must keep allocation to a minimum because collection is not yet enabled.

Overrides:

preCollectorSpawn in class Plan