/**
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* \file
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* Tunable parameters and debugging switches.
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*
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* Copyright 2001-2003 Ximian, Inc
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* Copyright 2003-2010 Novell, Inc.
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* Copyright 2011 Xamarin Inc (http://www.xamarin.com)
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* Copyright (C) 2012 Xamarin Inc
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*
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* Licensed under the MIT license. See LICENSE file in the project root for full license information.
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*/
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#ifndef __MONO_SGENCONF_H__
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#define __MONO_SGENCONF_H__
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#include <glib.h>
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/*Basic defines and static tunables */
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#if SIZEOF_VOID_P == 4
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typedef guint32 mword;
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#else
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typedef guint64 mword;
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#endif
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typedef mword SgenDescriptor;
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#define SGEN_DESCRIPTOR_NULL 0
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/*
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* Turning on heavy statistics will turn off the managed allocator and
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* the managed write barrier.
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*/
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// #define HEAVY_STATISTICS
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#ifdef HEAVY_STATISTICS
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#define HEAVY_STAT(x) x
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#else
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#define HEAVY_STAT(x)
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#endif
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/*
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* The binary protocol enables logging a lot of the GC ativity in a way that is not very
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* intrusive and produces a compact file that can be searched using a custom tool. This
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* option enables very fine-grained binary protocol events, which will make the GC a tiny
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* bit less efficient even if no binary protocol file is generated.
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*/
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//#define SGEN_HEAVY_BINARY_PROTOCOL
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/*
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* This extends the heavy binary protocol to record the provenance of an object
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* for every allocation.
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*/
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//#define SGEN_OBJECT_PROVENANCE
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/*
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* This enables checks whenever objects are enqueued in gray queues.
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* Right now the only check done is that we never enqueue nursery
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* pointers in the concurrent collector.
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*/
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//#define SGEN_CHECK_GRAY_OBJECT_ENQUEUE
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/*
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* This keeps track of where a gray object queue section is and
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* whether it is where it should be.
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*/
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//#define SGEN_CHECK_GRAY_OBJECT_SECTIONS
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/*
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* Enable this to check every reference update for null references and whether the update is
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* made in a worker thread. In only a few cases do we potentially update references by
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* writing nulls, so we assert in all the cases where it's not allowed. The concurrent
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* collector's worker thread is not allowed to update references at all, so we also assert
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* that we're not in the worker thread.
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*/
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//#define SGEN_CHECK_UPDATE_REFERENCE
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/*
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* Define this and use the "xdomain-checks" MONO_GC_DEBUG option to
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* have cross-domain checks in the write barrier.
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*/
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//#define XDOMAIN_CHECKS_IN_WBARRIER
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/*
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* Define this to get number of objects marked information in the
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* concurrent GC DTrace probes. Has a small performance impact, so
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* it's disabled by default.
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*/
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//#define SGEN_COUNT_NUMBER_OF_MAJOR_OBJECTS_MARKED
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/*
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* Object layout statistics gather a histogram of reference locations
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* over all scanned objects. We use this information to improve GC
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* descriptors to speed up scanning. This does not provide any
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* troubleshooting assistance (unless you are troubled in highly
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* unusual ways) and makes scanning slower.
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*/
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//#define SGEN_OBJECT_LAYOUT_STATISTICS
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#ifndef SGEN_HEAVY_BINARY_PROTOCOL
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#ifndef HEAVY_STATISTICS
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#define MANAGED_ALLOCATION
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#ifndef XDOMAIN_CHECKS_IN_WBARRIER
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#define MANAGED_WBARRIER
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#endif
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#endif
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#endif
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#if defined (HOST_WASM)
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#define DEFAULT_MAJOR SGEN_MAJOR_SERIAL
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#define DEFAULT_SWEEP_MODE SGEN_SWEEP_SERIAL
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#elif defined(HAVE_CONC_GC_AS_DEFAULT)
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/* Use concurrent major on deskstop platforms */
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#define DEFAULT_MAJOR SGEN_MAJOR_CONCURRENT
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#define DEFAULT_SWEEP_MODE SGEN_SWEEP_CONCURRENT
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#else
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#define DEFAULT_MAJOR SGEN_MAJOR_SERIAL
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#define DEFAULT_SWEEP_MODE SGEN_SWEEP_CONCURRENT
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#endif
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/*
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* Maximum level of debug to enable on this build.
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* Making this a constant enables us to put logging in a lot of places and
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* not pay its cost on release builds.
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*/
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#define SGEN_MAX_DEBUG_LEVEL 2
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/*
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* Maximum level of asserts to enable on this build.
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* FIXME replace all magic numbers with defines.
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*/
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#define SGEN_MAX_ASSERT_LEVEL 5
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#define GC_BITS_PER_WORD (sizeof (mword) * 8)
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/*Size of the section used by the copying GC. */
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#define SGEN_SIZEOF_GC_MEM_SECTION ((sizeof (GCMemSection) + 7) & ~7)
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/*
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* to quickly find the head of an object pinned by a conservative
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* address we keep track of the objects allocated for each
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* SGEN_SCAN_START_SIZE memory chunk in the nursery or other memory
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* sections. Larger values have less memory overhead and bigger
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* runtime cost. 4-8 KB are reasonable values.
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*/
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#define SGEN_SCAN_START_SIZE (4096*2)
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/*
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* Objects bigger then this go into the large object space. This size has a few
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* constraints. At least two of them must fit into a major heap block. It must also play
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* well with the run length GC descriptor, which encodes the object size.
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*/
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#define SGEN_MAX_SMALL_OBJ_SIZE 8000
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/*
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* This is the maximum ammount of memory we're willing to waste in order to speed up allocation.
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* Wastage comes in thre forms:
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*
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* -when building the nursery fragment list, small regions are discarded;
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* -when allocating memory from a fragment if it ends up below the threshold, we remove it from the fragment list; and
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* -when allocating a new tlab, we discard the remaining space of the old one
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*
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* Increasing this value speeds up allocation but will cause more frequent nursery collections as less space will be used.
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* Descreasing this value will cause allocation to be slower since we'll have to cycle thru more fragments.
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* 512 annedoctally keeps wastage under control and doesn't impact allocation performance too much.
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*/
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#define SGEN_MAX_NURSERY_WASTE 512
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/*
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* Minimum allowance for nursery allocations, as a multiple of the size of nursery.
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*
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* We allow at least this much allocation to happen to the major heap from multiple
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* minor collections before triggering a major collection.
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*
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* Bigger values increases throughput by allowing more garbage to sit in the major heap.
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* Smaller values leads to better memory effiency but more frequent major collections.
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*/
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#define SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO 4.0
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#define SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO 1.0
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#define SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO 10.0
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/*
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* How much more we allow the heap to grow before triggering another major collection
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*/
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#define SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO 0.33
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/*
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* Default ratio of memory we want to release in a major collection in relation to the the current heap size.
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*
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* A major collection target is to free a given amount of memory. This amount is a ratio of the major heap size.
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*
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* Values above 0.5 cause the heap to agressively grow when it's small and waste memory when it's big.
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* Lower values will produce more reasonable sized heaps when it's small, but will be suboptimal at large
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* sizes as they will use a small fraction only.
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*
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*/
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#define SGEN_DEFAULT_SAVE_TARGET_RATIO 0.5
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#define SGEN_MIN_SAVE_TARGET_RATIO 0.1
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#define SGEN_MAX_SAVE_TARGET_RATIO 2.0
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/*
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* Configurable cementing parameters.
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*
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* If there are too many pinned nursery objects with many references
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* from the major heap, the hash table size must be increased.
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*
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* The threshold is the number of references from the major heap to a
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* pinned nursery object which triggers cementing: if there are more
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* than that number of references, the pinned object is cemented until
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* the next major collection.
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*/
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#define SGEN_CEMENT_HASH_SHIFT 6
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#define SGEN_CEMENT_HASH_SIZE (1 << SGEN_CEMENT_HASH_SHIFT)
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#define SGEN_CEMENT_HASH(hv) (((hv) ^ ((hv) >> SGEN_CEMENT_HASH_SHIFT)) & (SGEN_CEMENT_HASH_SIZE - 1))
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#define SGEN_CEMENT_THRESHOLD 1000
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/*
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* Default values for the nursery size
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*/
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#define SGEN_DEFAULT_NURSERY_MIN_SIZE (1 << 19)
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#define SGEN_DEFAULT_NURSERY_SIZE (1 << 22)
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#define SGEN_DEFAULT_NURSERY_MAX_SIZE (1 << 25)
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/*
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* We are trying to keep pauses lower than this (ms). We use it for dynamic nursery
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* sizing heuristics. We are keeping leeway in order to be prepared for work-load
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* variations.
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*/
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#define SGEN_DEFAULT_MAX_PAUSE_TIME 30
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#define SGEN_DEFAULT_MAX_PAUSE_MARGIN 0.66f
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#define SGEN_PAUSE_MODE_MAX_PAUSE_MARGIN 0.5f
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/*
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* In practice, for nurseries smaller than this, the parallel minor tends to be
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* ineffective, even leading to regressions. Avoid using it for smaller nurseries.
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*/
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#define SGEN_PARALLEL_MINOR_MIN_NURSERY_SIZE (1 << 24)
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#endif
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