Summary: Employ PLABStats instances to record information about survivor and old PLABs, and use the recorded stats to adjust the sizes of survivor and old PLABS.
Reviewed-by: johnc, ysr
Contributed-by: NBrandon Mitchell <brandon@twitter.com>

Summary: Various cleanups as a prelude to introducing iterators for HeapRegions.
Reviewed-by: johnc, brutisso

7151532: DCmd for hotspot native memory tracking
Summary: Implementation of native memory tracking phase 1, which tracks VM native memory usage, and related DCmd
Reviewed-by: acorn, coleenp, fparain

Reviewed-by: azeemj, jmasa

Summary: Change the type of fields / variables / etc. that represent region counts and indeces from size_t to uint.
Reviewed-by: iveresov, brutisso, jmasa, jwilhelm

Summary: removed oop_verify_old_oop and allow_dirty. Also reviewed by: alexlamsl@gmail.com
Reviewed-by: jmasa, jwilhelm

Summary: Removed lots of dead code after some recent conc mark changes.
Reviewed-by: brutisso, johnc

Reviewed-by: tonyp, johnc

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: If we try to schedule an initial-mark GC in order to explicit start a conc mark cycle and it gets pre-empted by antoher GC, we should retry the attempt as long as it's appropriate for the GC cause.
Reviewed-by: brutisso, johnc

Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by: brutisso, 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: Parallelize the removal of self forwarding pointers etc. by wrapping in a HeapRegion closure, which is then wrapped inside an AbstractGangTask.
Reviewed-by: tonyp, iveresov

Summary: Introduce a flag that is set when a heap expansion attempt during a GC fails so that we do not consantly attempt to expand the heap when it's going to fail anyway. This not only prevents the excessive ergo output (which is generated when a region allocation fails) but also avoids excessive and ultimately unsuccessful expansion attempts.
Reviewed-by: jmasa, johnc

Summary: Cache workers' calculated starting heap region, used for parallel iteration over the collcection set, for subsequent reuse.
Reviewed-by: tonyp, brutisso

Summary: Change variables representing the number of GC workers to uint from int and size_t.  Change the parameter in work(int i) to work(uint worker_id).
Reviewed-by: brutisso, tonyp

Summary: Fixed G1CollectedHeap::is_in, added tests, cleaned up comments and made Space::is_in pure virtual.
Reviewed-by: brutisso, tonyp, jcoomes

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

Reviewed-by: johnc, brutisso, poonam

Summary: Keep track of all the old regions in the heap with a heap region set.
Reviewed-by: brutisso, johnc

Summary: Remove the extra guard to allow G1 to use ReduceInitialCardMarks
Reviewed-by: jmasa, tonyp, johnc, ysr

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: As a result of the changes for 7080389, an evacuation failure during an initial mark pause may result in some root objects not being marked. Pass whether the caller is a root scanning closure into the evacuation failure handling code so that the thread that successfully forwards an object to itself also marks the object.
Reviewed-by: ysr, brutisso, tonyp

Summary: Refactor code marking code in the evacuation pause copy closures so that an evacuated object is only marked by the thread that successfully copies it.
Reviewed-by: stefank, brutisso, tonyp

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: Extend and make more consistent the output from the G1PrintHeapRegions flag.
Reviewed-by: johnc, jmasa

Summary: Remove two unnecessary iterations over the collection set which are supposed to prepare the RSet's of the CSet regions for parallel iterations (we'll make sure this is done incrementally). I'll piggyback on this CR the removal of the G1_REM_SET_LOGGING code.
Reviewed-by: brutisso, johnc

Summary: Remove two unused parameters from the mem_allocate() method and update its uses accordingly.
Reviewed-by: stefank, johnc

Summary: Perform a heap verification after the first phase of G1's full GC using objects' mark words to determine liveness. The third parameter of the heap verification routines, which was used in G1 to determine which marking bitmap to use in liveness calculations, has been changed from a boolean to an enum with values defined for using the mark word, and the 'prev' and 'next' bitmaps.
Reviewed-by: tonyp, ysr

7042285: G1: native memory leak during humongous object allocation
6804436: G1: heap region indices should be size_t
Summary: A series of fixes and improvements to the HeapRegionSeq class: a) replace the _regions growable array with a standard C array, b) avoid de-allocating / re-allocating HeapRegion instances when the heap shrinks / grows (fix for 7042285), c) introduce fast method to map address to HeapRegion via a "biased" array pointer, d) embed the _hrs object in G1CollectedHeap, instead of pointing to it via an indirection, e) assume that all the regions added to the HeapRegionSeq instance are contiguous, f) replace int's with size_t's for indexes (and expand that to HeapRegion as part of 6804436), g) remove unnecessary / unused methods, h) rename a couple of fields (_alloc_search_start and _seq_bottom), i) fix iterate_from() not to always start from index 0 irrespective of the region passed to it, j) add a verification method to check the HeapRegionSeq assumptions, k) always call the wrappers for _hrs.iterate(), _hrs_length(), and _hrs.at() from G1CollectedHeap, not those methods directly, and l) unify the code that expands the sequence (by either re-using or creating a new HeapRegion) and make it robust wrt to a HeapRegion allocation failing.
Reviewed-by: stefank, johnc, brutisso

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: Implement a more accurate is_scavengable()
Reviewed-by: stefank, jcoomes, ysr

7035144: G1: nightly failure: Non-dirty cards in region that should be dirty (failures still exist...)
Summary: We should only undirty cards after we decide that they are not on a young region, not before. The fix also includes improvements to the verify_dirty_region() method which print out which cards were not found dirty.
Reviewed-by: johnc, brutisso

Summary: Added counters for jstat
Reviewed-by: tonyp, jwilhelm, stefank, ysr, johnc