2 * sgen-memory-governor.c: When to schedule collections based on
6 * Rodrigo Kumpera (rkumpera@novell.com)
8 * Copyright 2001-2003 Ximian, Inc
9 * Copyright 2003-2010 Novell, Inc.
10 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
11 * Copyright (C) 2012 Xamarin Inc
13 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
21 #include "mono/sgen/sgen-gc.h"
22 #include "mono/sgen/sgen-memory-governor.h"
23 #include "mono/sgen/sgen-thread-pool.h"
24 #include "mono/sgen/sgen-client.h"
26 #define MIN_MINOR_COLLECTION_ALLOWANCE ((mword)(DEFAULT_NURSERY_SIZE * default_allowance_nursery_size_ratio))
28 /*Heap limits and allocation knobs*/
29 static mword max_heap_size = ((mword)0)- ((mword)1);
30 static mword soft_heap_limit = ((mword)0) - ((mword)1);
32 static double default_allowance_nursery_size_ratio = SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO;
33 static double save_target_ratio = SGEN_DEFAULT_SAVE_TARGET_RATIO;
36 static mword allocated_heap;
37 static mword total_alloc = 0;
38 static mword total_alloc_max = 0;
42 static gboolean debug_print_allowance = FALSE;
45 /* use this to tune when to do a major/minor collection */
46 static mword major_collection_trigger_size;
48 static mword major_pre_sweep_heap_size;
49 static mword major_start_heap_size;
51 static mword last_major_num_sections = 0;
52 static mword last_los_memory_usage = 0;
54 static gboolean need_calculate_minor_collection_allowance;
56 /* The size of the LOS after the last major collection, after sweeping. */
57 static mword last_collection_los_memory_usage = 0;
59 static mword sgen_memgov_available_free_space (void);
62 /* GC trigger heuristics. */
65 sgen_memgov_calculate_minor_collection_allowance (void)
67 size_t new_major, new_heap_size, allowance_target, allowance;
70 if (!need_calculate_minor_collection_allowance)
73 SGEN_ASSERT (0, major_collector.have_swept (), "Can only calculate allowance if heap is swept");
75 new_major = major_collector.get_bytes_survived_last_sweep ();
76 new_heap_size = new_major + last_collection_los_memory_usage;
79 * We allow the heap to grow by one third its current size before we start the next
82 allowance_target = new_heap_size * SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO;
84 allowance = MAX (allowance_target, MIN_MINOR_COLLECTION_ALLOWANCE);
87 * For the concurrent collector, we decrease the allowance relative to the memory
88 * growth during the M&S phase, survival rate of the collection and the allowance
91 decrease = (major_pre_sweep_heap_size - major_start_heap_size) * ((float)new_heap_size / major_pre_sweep_heap_size) * (SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO + 1);
92 if (decrease > allowance)
94 allowance -= decrease;
96 if (new_heap_size + allowance > soft_heap_limit) {
97 if (new_heap_size > soft_heap_limit)
98 allowance = MIN_MINOR_COLLECTION_ALLOWANCE;
100 allowance = MAX (soft_heap_limit - new_heap_size, MIN_MINOR_COLLECTION_ALLOWANCE);
103 /* FIXME: Why is this here? */
104 if (major_collector.free_swept_blocks)
105 major_collector.free_swept_blocks (allowance);
107 major_collection_trigger_size = new_heap_size + allowance;
109 need_calculate_minor_collection_allowance = FALSE;
111 if (debug_print_allowance) {
112 SGEN_LOG (0, "Surviving sweep: %ld bytes (%ld major, %ld LOS)", (long)new_heap_size, (long)new_major, (long)last_collection_los_memory_usage);
113 SGEN_LOG (0, "Allowance: %ld bytes", (long)allowance);
114 SGEN_LOG (0, "Trigger size: %ld bytes", (long)major_collection_trigger_size);
121 return major_collector.get_num_major_sections () * major_collector.section_size + los_memory_usage;
125 sgen_need_major_collection (mword space_needed)
129 if (sgen_concurrent_collection_in_progress ()) {
130 heap_size = get_heap_size ();
132 if (heap_size <= major_collection_trigger_size)
136 * The more the heap grows, the more we need to decrease the allowance above,
137 * in order to have similar trigger sizes as the synchronous collector.
138 * If the heap grows so much that we would need to have a negative allowance,
139 * we force the finishing of the collection, to avoid increased memory usage.
141 if ((heap_size - major_start_heap_size) > major_start_heap_size * SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO)
146 /* FIXME: This is a cop-out. We should have some way of figuring this out. */
147 if (!major_collector.have_swept ())
150 if (space_needed > sgen_memgov_available_free_space ())
153 sgen_memgov_calculate_minor_collection_allowance ();
155 heap_size = get_heap_size ();
157 return heap_size > major_collection_trigger_size;
161 sgen_memgov_minor_collection_start (void)
166 sgen_memgov_minor_collection_end (void)
171 sgen_memgov_major_pre_sweep (void)
173 if (sgen_concurrent_collection_in_progress ()) {
174 major_pre_sweep_heap_size = get_heap_size ();
176 /* We decrease the allowance only in the concurrent case */
177 major_pre_sweep_heap_size = major_start_heap_size;
182 sgen_memgov_major_collection_start (void)
184 need_calculate_minor_collection_allowance = TRUE;
185 major_start_heap_size = get_heap_size ();
187 if (debug_print_allowance) {
188 SGEN_LOG (0, "Starting collection with heap size %ld bytes", (long)major_start_heap_size);
193 sgen_memgov_major_collection_end (gboolean forced)
195 last_collection_los_memory_usage = los_memory_usage;
198 sgen_get_major_collector ()->finish_sweeping ();
199 sgen_memgov_calculate_minor_collection_allowance ();
204 sgen_memgov_collection_start (int generation)
209 sgen_memgov_collection_end (int generation, GGTimingInfo* info, int info_count)
212 for (i = 0; i < info_count; ++i) {
213 if (info[i].generation != -1)
214 sgen_client_log_timing (&info [i], last_major_num_sections, last_los_memory_usage);
216 last_major_num_sections = major_collector.get_num_major_sections ();
220 Global GC memory tracking.
221 This tracks the total usage of memory by the GC. This includes
222 managed and unmanaged memory.
226 prot_flags_for_activate (int activate)
228 unsigned long prot_flags = activate? MONO_MMAP_READ|MONO_MMAP_WRITE: MONO_MMAP_NONE;
229 return prot_flags | MONO_MMAP_PRIVATE | MONO_MMAP_ANON;
233 sgen_assert_memory_alloc (void *ptr, size_t requested_size, const char *assert_description)
235 if (ptr || !assert_description)
237 fprintf (stderr, "Error: Garbage collector could not allocate %zu bytes of memory for %s.\n", requested_size, assert_description);
242 * Allocate a big chunk of memory from the OS (usually 64KB to several megabytes).
243 * This must not require any lock.
246 sgen_alloc_os_memory (size_t size, SgenAllocFlags flags, const char *assert_description)
250 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
252 ptr = mono_valloc (0, size, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
253 sgen_assert_memory_alloc (ptr, size, assert_description);
255 SGEN_ATOMIC_ADD_P (total_alloc, size);
256 total_alloc_max = MAX (total_alloc_max, total_alloc);
261 /* size must be a power of 2 */
263 sgen_alloc_os_memory_aligned (size_t size, mword alignment, SgenAllocFlags flags, const char *assert_description)
267 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
269 ptr = mono_valloc_aligned (size, alignment, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
270 sgen_assert_memory_alloc (ptr, size, assert_description);
272 SGEN_ATOMIC_ADD_P (total_alloc, size);
273 total_alloc_max = MAX (total_alloc_max, total_alloc);
279 * Free the memory returned by sgen_alloc_os_memory (), returning it to the OS.
282 sgen_free_os_memory (void *addr, size_t size, SgenAllocFlags flags)
284 g_assert (!(flags & ~SGEN_ALLOC_HEAP));
286 mono_vfree (addr, size);
287 SGEN_ATOMIC_ADD_P (total_alloc, -(gssize)size);
288 total_alloc_max = MAX (total_alloc_max, total_alloc);
292 sgen_gc_get_total_heap_allocation (void)
300 This limit the max size of the heap. It takes into account
301 only memory actively in use to hold heap objects and not
302 for other parts of the GC.
305 sgen_memgov_available_free_space (void)
307 return max_heap_size - MIN (allocated_heap, max_heap_size);
311 sgen_memgov_release_space (mword size, int space)
313 SGEN_ATOMIC_ADD_P (allocated_heap, -(gssize)size);
317 sgen_memgov_try_alloc_space (mword size, int space)
319 if (sgen_memgov_available_free_space () < size) {
320 SGEN_ASSERT (4, !sgen_thread_pool_is_thread_pool_thread (mono_native_thread_id_get ()), "Memory shouldn't run out in worker thread");
324 SGEN_ATOMIC_ADD_P (allocated_heap, size);
325 sgen_client_total_allocated_heap_changed (allocated_heap);
330 sgen_memgov_init (size_t max_heap, size_t soft_limit, gboolean debug_allowance, double allowance_ratio, double save_target)
333 soft_heap_limit = soft_limit;
335 debug_print_allowance = debug_allowance;
336 major_collection_trigger_size = MIN_MINOR_COLLECTION_ALLOWANCE;
338 mono_counters_register ("Memgov alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_VARIABLE, &total_alloc);
339 mono_counters_register ("Memgov max alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_MONOTONIC, &total_alloc_max);
344 if (max_heap < soft_limit) {
345 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Setting to minimum.", "`max-heap-size` must be at least as large as `soft-heap-limit`.");
346 max_heap = soft_limit;
349 if (max_heap < sgen_nursery_size * 4) {
350 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Setting to minimum.", "`max-heap-size` must be at least 4 times as large as `nursery size`.");
351 max_heap = sgen_nursery_size * 4;
353 max_heap_size = max_heap - sgen_nursery_size;
356 default_allowance_nursery_size_ratio = allowance_ratio;
359 save_target_ratio = save_target;