285 lines
12 KiB
C++
285 lines
12 KiB
C++
/*
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* Copyright (c) 2011, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_GC_G1_G1ALLOCREGION_HPP
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#define SHARE_GC_G1_G1ALLOCREGION_HPP
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#include "gc/g1/heapRegion.hpp"
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#include "gc/g1/g1EvacStats.hpp"
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#include "gc/g1/g1HeapRegionAttr.hpp"
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class G1CollectedHeap;
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// A class that holds a region that is active in satisfying allocation
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// requests, potentially issued in parallel. When the active region is
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// full it will be retired and replaced with a new one. The
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// implementation assumes that fast-path allocations will be lock-free
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// and a lock will need to be taken when the active region needs to be
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// replaced.
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class G1AllocRegion {
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private:
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// The active allocating region we are currently allocating out
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// of. The invariant is that if this object is initialized (i.e.,
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// init() has been called and release() has not) then _alloc_region
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// is either an active allocating region or the dummy region (i.e.,
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// it can never be NULL) and this object can be used to satisfy
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// allocation requests. If this object is not initialized
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// (i.e. init() has not been called or release() has been called)
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// then _alloc_region is NULL and this object should not be used to
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// satisfy allocation requests (it was done this way to force the
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// correct use of init() and release()).
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HeapRegion* volatile _alloc_region;
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// It keeps track of the distinct number of regions that are used
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// for allocation in the active interval of this object, i.e.,
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// between a call to init() and a call to release(). The count
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// mostly includes regions that are freshly allocated, as well as
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// the region that is re-used using the set() method. This count can
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// be used in any heuristics that might want to bound how many
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// distinct regions this object can used during an active interval.
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uint _count;
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// When we set up a new active region we save its used bytes in this
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// field so that, when we retire it, we can calculate how much space
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// we allocated in it.
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size_t _used_bytes_before;
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// When true, indicates that allocate calls should do BOT updates.
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const bool _bot_updates;
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// Useful for debugging and tracing.
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const char* _name;
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// A dummy region (i.e., it's been allocated specially for this
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// purpose and it is not part of the heap) that is full (i.e., top()
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// == end()). When we don't have a valid active region we make
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// _alloc_region point to this. This allows us to skip checking
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// whether the _alloc_region is NULL or not.
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static HeapRegion* _dummy_region;
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// After a region is allocated by alloc_new_region, this
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// method is used to set it as the active alloc_region
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void update_alloc_region(HeapRegion* alloc_region);
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// Allocate a new active region and use it to perform a word_size
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// allocation. The force parameter will be passed on to
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// G1CollectedHeap::allocate_new_alloc_region() and tells it to try
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// to allocate a new region even if the max has been reached.
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HeapWord* new_alloc_region_and_allocate(size_t word_size, bool force);
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protected:
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// Reset the alloc region to point a the dummy region.
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void reset_alloc_region();
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// Perform a non-MT-safe allocation out of the given region.
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inline HeapWord* allocate(HeapRegion* alloc_region,
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size_t word_size);
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// Perform a MT-safe allocation out of the given region.
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inline HeapWord* par_allocate(HeapRegion* alloc_region,
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size_t word_size);
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// Perform a MT-safe allocation out of the given region, with the given
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// minimum and desired size. Returns the actual size allocated (between
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// minimum and desired size) in actual_word_size if the allocation has been
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// successful.
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inline HeapWord* par_allocate(HeapRegion* alloc_region,
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size_t min_word_size,
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size_t desired_word_size,
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size_t* actual_word_size);
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// Ensure that the region passed as a parameter has been filled up
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// so that noone else can allocate out of it any more.
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// Returns the number of bytes that have been wasted by filled up
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// the space.
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size_t fill_up_remaining_space(HeapRegion* alloc_region);
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// Retire the active allocating region. If fill_up is true then make
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// sure that the region is full before we retire it so that no one
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// else can allocate out of it.
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// Returns the number of bytes that have been filled up during retire.
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virtual size_t retire(bool fill_up);
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size_t retire_internal(HeapRegion* alloc_region, bool fill_up);
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// For convenience as subclasses use it.
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static G1CollectedHeap* _g1h;
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virtual HeapRegion* allocate_new_region(size_t word_size, bool force) = 0;
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virtual void retire_region(HeapRegion* alloc_region,
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size_t allocated_bytes) = 0;
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G1AllocRegion(const char* name, bool bot_updates);
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public:
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static void setup(G1CollectedHeap* g1h, HeapRegion* dummy_region);
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HeapRegion* get() const {
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HeapRegion * hr = _alloc_region;
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// Make sure that the dummy region does not escape this class.
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return (hr == _dummy_region) ? NULL : hr;
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}
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uint count() { return _count; }
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// The following two are the building blocks for the allocation method.
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// First-level allocation: Should be called without holding a
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// lock. It will try to allocate lock-free out of the active region,
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// or return NULL if it was unable to.
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inline HeapWord* attempt_allocation(size_t word_size);
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// Perform an allocation out of the current allocation region, with the given
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// minimum and desired size. Returns the actual size allocated (between
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// minimum and desired size) in actual_word_size if the allocation has been
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// successful.
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// Should be called without holding a lock. It will try to allocate lock-free
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// out of the active region, or return NULL if it was unable to.
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inline HeapWord* attempt_allocation(size_t min_word_size,
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size_t desired_word_size,
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size_t* actual_word_size);
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// Second-level allocation: Should be called while holding a
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// lock. It will try to first allocate lock-free out of the active
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// region or, if it's unable to, it will try to replace the active
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// alloc region with a new one. We require that the caller takes the
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// appropriate lock before calling this so that it is easier to make
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// it conform to its locking protocol.
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inline HeapWord* attempt_allocation_locked(size_t word_size);
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// Same as attempt_allocation_locked(size_t, bool), but allowing specification
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// of minimum word size of the block in min_word_size, and the maximum word
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// size of the allocation in desired_word_size. The actual size of the block is
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// returned in actual_word_size.
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inline HeapWord* attempt_allocation_locked(size_t min_word_size,
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size_t desired_word_size,
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size_t* actual_word_size);
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// Should be called to allocate a new region even if the max of this
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// type of regions has been reached. Should only be called if other
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// allocation attempts have failed and we are not holding a valid
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// active region.
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inline HeapWord* attempt_allocation_force(size_t word_size);
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// Should be called before we start using this object.
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virtual void init();
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// This can be used to set the active region to a specific
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// region. (Use Example: we try to retain the last old GC alloc
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// region that we've used during a GC and we can use set() to
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// re-instate it at the beginning of the next GC.)
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void set(HeapRegion* alloc_region);
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// Should be called when we want to release the active region which
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// is returned after it's been retired.
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virtual HeapRegion* release();
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void trace(const char* str,
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size_t min_word_size = 0,
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size_t desired_word_size = 0,
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size_t actual_word_size = 0,
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HeapWord* result = NULL) PRODUCT_RETURN;
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};
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class MutatorAllocRegion : public G1AllocRegion {
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private:
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// Keeps track of the total waste generated during the current
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// mutator phase.
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size_t _wasted_bytes;
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// Retained allocation region. Used to lower the waste generated
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// during mutation by having two active regions if the free space
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// in a region about to be retired still could fit a TLAB.
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HeapRegion* volatile _retained_alloc_region;
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// Decide if the region should be retained, based on the free size
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// in it and the free size in the currently retained region, if any.
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bool should_retain(HeapRegion* region);
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protected:
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virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
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virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
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virtual size_t retire(bool fill_up);
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public:
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MutatorAllocRegion()
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: G1AllocRegion("Mutator Alloc Region", false /* bot_updates */),
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_wasted_bytes(0),
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_retained_alloc_region(NULL) { }
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// Returns the combined used memory in the current alloc region and
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// the retained alloc region.
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size_t used_in_alloc_regions();
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// Perform an allocation out of the retained allocation region, with the given
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// minimum and desired size. Returns the actual size allocated (between
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// minimum and desired size) in actual_word_size if the allocation has been
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// successful.
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// Should be called without holding a lock. It will try to allocate lock-free
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// out of the retained region, or return NULL if it was unable to.
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inline HeapWord* attempt_retained_allocation(size_t min_word_size,
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size_t desired_word_size,
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size_t* actual_word_size);
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// This specialization of release() makes sure that the retained alloc
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// region is retired and set to NULL.
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virtual HeapRegion* release();
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virtual void init();
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};
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// Common base class for allocation regions used during GC.
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class G1GCAllocRegion : public G1AllocRegion {
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protected:
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G1EvacStats* _stats;
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G1HeapRegionAttr::region_type_t _purpose;
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virtual HeapRegion* allocate_new_region(size_t word_size, bool force);
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virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes);
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virtual size_t retire(bool fill_up);
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G1GCAllocRegion(const char* name, bool bot_updates, G1EvacStats* stats, G1HeapRegionAttr::region_type_t purpose)
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: G1AllocRegion(name, bot_updates), _stats(stats), _purpose(purpose) {
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assert(stats != NULL, "Must pass non-NULL PLAB statistics");
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}
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};
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class SurvivorGCAllocRegion : public G1GCAllocRegion {
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public:
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SurvivorGCAllocRegion(G1EvacStats* stats)
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: G1GCAllocRegion("Survivor GC Alloc Region", false /* bot_updates */, stats, G1HeapRegionAttr::Young) { }
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};
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class OldGCAllocRegion : public G1GCAllocRegion {
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public:
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OldGCAllocRegion(G1EvacStats* stats)
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: G1GCAllocRegion("Old GC Alloc Region", true /* bot_updates */, stats, G1HeapRegionAttr::Old) { }
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// This specialization of release() makes sure that the last card that has
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// been allocated into has been completely filled by a dummy object. This
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// avoids races when remembered set scanning wants to update the BOT of the
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// last card in the retained old gc alloc region, and allocation threads
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// allocating into that card at the same time.
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virtual HeapRegion* release();
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};
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#endif // SHARE_GC_G1_G1ALLOCREGION_HPP
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