2 * sgen-conf.h: Tunable parameters and debugging switches.
4 * Copyright 2001-2003 Ximian, Inc
5 * Copyright 2003-2010 Novell, Inc.
6 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
7 * Copyright (C) 2012 Xamarin Inc
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Library General Public
11 * License 2.0 as published by the Free Software Foundation;
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License 2.0 along with this library; if not, write to the Free
20 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 #ifndef __MONO_SGENCONF_H__
23 #define __MONO_SGENCONF_H__
25 /*Basic defines and static tunables */
27 #if SIZEOF_VOID_P == 4
28 typedef guint32 mword;
29 #define MWORD_MAX_VALUE ((uint32_t) 0xffffffff)
31 typedef guint64 mword;
32 #define MWORD_MAX_VALUE (G_MAXUINT64)
37 * Turning on heavy statistics will turn off the managed allocator and
38 * the managed write barrier.
40 // #define HEAVY_STATISTICS
43 * Define this to allow the user to change the nursery size by
44 * specifying its value in the MONO_GC_PARAMS environmental
45 * variable. See mono_gc_base_init for details.
51 * If this is set, the nursery is aligned to an address aligned to its size, ie.
52 * a 1MB nursery will be aligned to an address divisible by 1MB. This allows us to
53 * speed up ptr_in_nursery () checks which are very frequent. This requires the
54 * nursery size to be a compile time constant.
56 #define SGEN_ALIGN_NURSERY 1
59 * The binary protocol enables logging a lot of the GC ativity in a way that is not very
60 * intrusive and produces a compact file that can be searched using a custom tool. This
61 * option enables very fine-grained binary protocol events, which will make the GC a tiny
62 * bit less efficient even if no binary protocol file is generated.
64 //#define SGEN_HEAVY_BINARY_PROTOCOL
67 * This enables checks whenever objects are enqueued in gray queues.
68 * Right now the only check done is that we never enqueue nursery
69 * pointers in the concurrent collector.
71 //#define SGEN_CHECK_GRAY_OBJECT_ENQUEUE
74 * This keeps track of where a gray object queue section is and
75 * whether it is where it should be.
77 //#define SGEN_CHECK_GRAY_OBJECT_SECTIONS
80 * Define this and use the "xdomain-checks" MONO_GC_DEBUG option to
81 * have cross-domain checks in the write barrier.
83 //#define XDOMAIN_CHECKS_IN_WBARRIER
86 * Define this to get number of objects marked information in the
87 * concurrent GC DTrace probes. Has a small performance impact, so
88 * it's disabled by default.
90 //#define SGEN_COUNT_NUMBER_OF_MAJOR_OBJECTS_MARKED
93 * Object layout statistics gather a histogram of reference locations
94 * over all scanned objects. We use this information to improve GC
95 * descriptors to speed up scanning. This does not provide any
96 * troubleshooting assistance (unless you are troubled in highly
97 * unusual ways) and makes scanning slower.
99 //#define SGEN_OBJECT_LAYOUT_STATISTICS
101 #ifndef SGEN_HEAVY_BINARY_PROTOCOL
102 #ifndef HEAVY_STATISTICS
103 #define MANAGED_ALLOCATION
104 #ifndef XDOMAIN_CHECKS_IN_WBARRIER
105 #define MANAGED_WBARRIER
111 * Maximum level of debug to enable on this build.
112 * Making this a constant enables us to put logging in a lot of places and
113 * not pay its cost on release builds.
115 #define SGEN_MAX_DEBUG_LEVEL 2
118 * Maximum level of asserts to enable on this build.
119 * FIXME replace all magic numbers with defines.
121 #define SGEN_MAX_ASSERT_LEVEL 5
124 #define GC_BITS_PER_WORD (sizeof (mword) * 8)
126 /*Size of the section used by the copying GC. */
127 #define SGEN_SIZEOF_GC_MEM_SECTION ((sizeof (GCMemSection) + 7) & ~7)
130 * to quickly find the head of an object pinned by a conservative
131 * address we keep track of the objects allocated for each
132 * SGEN_SCAN_START_SIZE memory chunk in the nursery or other memory
133 * sections. Larger values have less memory overhead and bigger
134 * runtime cost. 4-8 KB are reasonable values.
136 #define SGEN_SCAN_START_SIZE (4096*2)
139 * Objects bigger then this go into the large object space. This size
140 * has a few constraints. It must fit into the major heap, which in
141 * the case of the copying collector means that it must fit into a
142 * pinned chunk. It must also play well with the GC descriptors, some
143 * of which (DESC_TYPE_RUN_LENGTH, DESC_TYPE_SMALL_BITMAP) encode the
146 #define SGEN_MAX_SMALL_OBJ_SIZE 8000
149 * This is the maximum ammount of memory we're willing to waste in order to speed up allocation.
150 * Wastage comes in thre forms:
152 * -when building the nursery fragment list, small regions are discarded;
153 * -when allocating memory from a fragment if it ends up below the threshold, we remove it from the fragment list; and
154 * -when allocating a new tlab, we discard the remaining space of the old one
156 * Increasing this value speeds up allocation but will cause more frequent nursery collections as less space will be used.
157 * Descreasing this value will cause allocation to be slower since we'll have to cycle thru more fragments.
158 * 512 annedoctally keeps wastage under control and doesn't impact allocation performance too much.
160 #define SGEN_MAX_NURSERY_WASTE 512
164 * Minimum allowance for nursery allocations, as a multiple of the size of nursery.
166 * We allow at least this much allocation to happen to the major heap from multiple
167 * minor collections before triggering a major collection.
169 * Bigger values increases throughput by allowing more garbage to sit in the major heap.
170 * Smaller values leads to better memory effiency but more frequent major collections.
172 #define SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO 4.0
174 #define SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO 1.0
175 #define SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO 10.0
178 * Default ratio of memory we want to release in a major collection in relation to the the current heap size.
180 * A major collection target is to free a given amount of memory. This amount is a ratio of the major heap size.
182 * Values above 0.5 cause the heap to agressively grow when it's small and waste memory when it's big.
183 * Lower values will produce more reasonable sized heaps when it's small, but will be suboptimal at large
184 * sizes as they will use a small fraction only.
187 #define SGEN_DEFAULT_SAVE_TARGET_RATIO 0.5
189 #define SGEN_MIN_SAVE_TARGET_RATIO 0.1
190 #define SGEN_MAX_SAVE_TARGET_RATIO 2.0
193 * Configurable cementing parameters.
195 * The hash table size should be a prime. If there are too many
196 * pinned nursery objects with many references from the major heap,
197 * this number must be increased.
199 * The threshold is the number of references from the major heap to a
200 * pinned nursery object which triggers cementing: if there are more
201 * than that number of references, the pinned object is cemented until
202 * the next major collection.
204 #define SGEN_CEMENT_HASH_SIZE 61
205 #define SGEN_CEMENT_THRESHOLD 1000