Summary: Revamp of the mechanism that chooses old regions for inclusion in the CSet. It simplifies the code and introduces min and max bounds on the number of old regions added to the CSet at each mixed GC to avoid pathological cases. It also ensures that when we do a mixed GC we'll always find old regions to add to the CSet (i.e., it eliminates the case where a mixed GC will collect no old regions which can happen today).
Reviewed-by: johnc, brutisso

Summary: Re-enable survivors during the initial-mark pause. Afterwards, the concurrent marking threads have to scan them and mark everything reachable from them. The next GC will have to wait for the survivors to be scanned.
Reviewed-by: brutisso, johnc

7132311: G1: assert((s == klass->oop_size(this)) || (Universe::heap()->is_gc_active() && ((is_typeArray()...
Summary: Move the check for when to call collect() to before we do a humongous object allocation
Reviewed-by: stefank, tonyp

Reviewed-by: tonyp, johnc

Summary: This change simplifies the interaction between GC and concurrent marking. By disabling survivor spaces during the initial-mark pause we don't need to propagate marks of objects we copy during each GC (since we never need to copy an explicitly marked object).
Reviewed-by: johnc, brutisso

Summary: Use a percentage of -Xms as min and another percentage of -Xmx as max for the young gen size
Reviewed-by: tonyp, johnc

Summary: Renamed partially-young GCs as mixed and fully-young GCs as young. Change all external output that includes those terms (GC log and GC ergo log) as well as any comments, fields, methods, etc. The changeset also includes very minor code tidying up (added some curly brackets).
Reviewed-by: johnc, brutisso

Summary: Make sure that the updates to the RS length and inc CSet predicted time are updated in an MT-safe way.
Reviewed-by: brutisso, iveresov

Summary: Parallelize the serial code that was used to mark objects reachable from survivor objects in the collection set. Some minor improvments in the timers used to track the freeing of the collection set along with some tweaks to PrintGCDetails.
Reviewed-by: tonyp, brutisso

Summary: Race between the VM thread reading G1CollectedHeap::_mark_in_progress and it being set by the concurrent mark thread when concurrent marking is aborted by a full GC. Have the concurrent mark thread join the SuspendibleThreadSet before changing the marking state.
Reviewed-by: tonyp, brutisso

7102445: G1: Unnecessary Resource allocations during RSet scanning
Summary: Add a new per-worker thread line in the PrintGCDetails output. GC Worker Other is the difference between the elapsed time for the parallel phase of the evacuation pause and the sum of the times of the sub-phases (external root scanning, mark stack scanning, RSet updating, RSet scanning, object copying, and termination) for that worker. During RSet scanning, stack allocate DirtyCardToOopClosure objects; allocating these in a resource area was causing abnormally high GC Worker Other times while the worker thread freed ResourceArea chunks.
Reviewed-by: tonyp, jwilhelm, brutisso

Summary: Removed unused fields and methods, removed the G1CollectoryPolicy_BestRegionsFirst class and folded its functionality into the G1CollectorPolicy class.
Reviewed-by: ysr, brutisso, jcoomes

Summary: Fixed a few inconsistencies in the monitoring data, in particular when reported from jstat.
Reviewed-by: jmasa, brutisso, johnc

Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

Summary: Make G1 handle young gen size command line flags more consistently
Reviewed-by: tonyp, jwilhelm

Summary: Fixed inconsistencies and mistakes in the young list target length calculations so that a) the calculated target length is optimal (before, it was not), b) other parameters like max survivor size and max gc locker eden expansion are always consistent with the calculated target length (before, they were not always), and c) the resulting target length was always bound by desired min and max values (before, it was not).
Reviewed-by: brutisso, johnc

Summary: It introduces ergonomic decision logging in G1 for the following heuristics: heap sizing, collection set construction, concurrent cycle initiation, and partially-young GC start/end. The code has a bit of refactoring in a few places to make the decision logging possible. It also replaces alternative ad-hoc logging that we have under different parameters and switches (G1_DEBUG, G1PolicyVerbose).
Reviewed-by: johnc, ysr

7081064: G1: remove develop params G1FixedSurvivorSpaceSize, G1FixedTenuringThreshold, and G1FixedEdenSize
Summary: Remove three develop parameters we don't use.
Reviewed-by: brutisso, jwilhelm

Summary: Removed the possibility to turn off generational mode for G1.
Reviewed-by: johnc, ysr, tonyp

Summary: Refactor the allocation code during GC to use the G1AllocRegion abstraction. Use separate subclasses of G1AllocRegion for survivor and old regions. Avoid BOT updates and dirty survivor cards incrementally for the former.
Reviewed-by: brutisso, johnc, ysr

Summary: Select number of GC threads dynamically based on heap usage and number of Java threads
Reviewed-by: johnc, ysr, jcoomes

Summary: Major cleanup of the G1CollectorPolicy class. It removes a lot of unused fields and methods and also consolidates replicated information (mainly various ways of counting the number of CSet regions) into one copy.
Reviewed-by: johnc, brutisso

Summary: In root processing, move the scanning of the reference processor's discovered lists to before RSet updating and scanning. When scanning the reference processor's discovered lists, use a buffering closure so that the time spent copying any reference object is correctly attributed. Also removed a couple of unused and irrelevant timers.
Reviewed-by: ysr, jmasa

Summary: This changeset extends the logging information generated by +PrintGCDetails to also print out separate size transitions for the eden, survivors, and old regions.
Reviewed-by: ysr, brutisso

Summary: Changed default value of WorkStealingYieldsBeforeSleep from 1000 to 5000. Added more information to G1 pause logging.
Reviewed-by: jwilhelm, tonyp, jmasa

Summary: Allow the eden to the expanded up to a point when the GC locker is active.
Reviewed-by: jwilhelm, johnc, ysr, jcoomes

Summary: Replaced MakeDeps and the includeDB files with more standardized solutions.
Reviewed-by: coleenp, kvn, kamg

Summary: This change revamps the slow allocation path of G1. Improvements include the following: a) Allocations directly to old regions are now totally banned. G1 now only allows allocations out of young regions (with the only exception being humongous regions). b) The thread that allocates a new region (which is now guaranteed to be young) does not dirty all its cards. Each thread that successfully allocates out of a young region is now responsible for dirtying the cards that corresponding to the "block" that just got allocated. c) allocate_new_tlab() and mem_allocate() are now implemented differently and TLAB allocations are only done by allocate_new_tlab(). d) If a thread schedules an evacuation pause in order to satisfy an allocation request, it will perform the allocation at the end of the safepoint so that the thread that initiated the GC also gets "first pick" of any space made available by the GC. e) If a thread is unable to allocate a humongous object it will schedule an evacuation pause in case it reclaims enough regions so that the humongous allocation can be satisfied aftewards. f) The G1 policy is more careful to set the young list target length to be the survivor number +1. g) Lots of code tidy up, removal, refactoring to make future changes easier.
Reviewed-by: johnc, ysr

Summary: As part of 6944166 we disabled the concept of abandoned pauses (i.e., if the collection set is empty, we would still try to do a pause even if it is to update the RSets and scan the roots). This changeset removes the code and structures associated with abandoned pauses.
Reviewed-by: iveresov, johnc

Summary: The per-worker _new_refs array is used to hold references that point into the collection set. It is populated during RSet updating and subsequently processed. In the event of an evacuation failure it processed again to recreate the RSets of regions in the collection set. Remove the per-worker _new_refs array by processing the references directly. Use a DirtyCardQueue to hold the cards containing the references so that the RSets of regions in the collection set can be recreated when handling an evacuation failure.
Reviewed-by: iveresov, jmasa, tonyp

Summary: G1 was not handling explicit GCs correctly in many ways. It does now. See the CR for the list of improvements contained in this changeset.
Reviewed-by: iveresov, ysr, johnc

Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair

Summary: Small improvements to G1's PrintGCDetails output. It also includes minor formatting details.
Reviewed-by: ysr, johnc

6871109: G1: remove the concept of the scan only prefix
Summary: Removed scan only regions and associated code. The young portion of the collection set is now constructed incrementally - when a young region is retired as the current allocation region it is added to the collection set.
Reviewed-by: apetrusenko, iveresov, tonyp

Summary: Make sure that two marking cycles do not overlap, i.e., a new one can only start after the concurrent marking thread finishes all its work. In the fix I piggy-back a couple of minor extra fixes: some general code reformatting for consistency (only around the code I modified), the removal of a field (G1CollectorPolicy::_should_initiate_conc_mark) which doesn't seem to be used at all (it's only set but never read), as well as moving the "is GC locker active" test earlier into the G1 pause / Full GC and using a more appropriate method for it.
Reviewed-by: johnc, jmasa, jcoomes, ysr

Summary: Remove the G1GCPercent parameter, that specifies the desired GC overhead percentage in G1, and observe the GCTimeRatio parameter instead.
Reviewed-by: jmasa, johnc

Summary: Reworked the concurrent refinement: threads activation, feedback-based threshold adjustment, other miscellaneous fixes.
Reviewed-by: apetrusenko, tonyp

Summary: The first worker thread is delayed when entering the GC because it clears the card count table that is used in identifying hot cards. Replace the card count table with a dynamically sized evicting hash table that includes an epoch based counter.
Reviewed-by: iveresov, tonyp

Summary: Instead of the region size being hard-coded, allow the user to set it.
Reviewed-by: jmasa, johnc, apetrusenko

Summary: Removing the concurrent overhead tracker from G1, along with the GC overhead reporter and the G1AccountConcurrentOverhead (both of which rely on the the concurrent overhead tracker).
Reviewed-by: iveresov, johnc