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 * This library is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU Library General Public
15 * License 2.0 as published by the Free Software Foundation;
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License 2.0 along with this library; if not, write to the Free
24 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
32 #include "mono/sgen/sgen-gc.h"
33 #include "mono/sgen/sgen-memory-governor.h"
34 #include "mono/sgen/sgen-thread-pool.h"
35 #include "mono/sgen/sgen-client.h"
37 #define MIN_MINOR_COLLECTION_ALLOWANCE ((mword)(DEFAULT_NURSERY_SIZE * default_allowance_nursery_size_ratio))
39 /*Heap limits and allocation knobs*/
40 static mword max_heap_size = ((mword)0)- ((mword)1);
41 static mword soft_heap_limit = ((mword)0) - ((mword)1);
43 static double default_allowance_nursery_size_ratio = SGEN_DEFAULT_ALLOWANCE_NURSERY_SIZE_RATIO;
44 static double save_target_ratio = SGEN_DEFAULT_SAVE_TARGET_RATIO;
47 static mword allocated_heap;
48 static mword total_alloc = 0;
49 static mword total_alloc_max = 0;
53 static gboolean debug_print_allowance = FALSE;
56 /* use this to tune when to do a major/minor collection */
57 static mword major_collection_trigger_size;
59 static mword last_major_num_sections = 0;
60 static mword last_los_memory_usage = 0;
62 static gboolean need_calculate_minor_collection_allowance;
64 /* The size of the LOS after the last major collection, after sweeping. */
65 static mword last_collection_los_memory_usage = 0;
67 static mword sgen_memgov_available_free_space (void);
70 /* GC trigger heuristics. */
73 sgen_memgov_calculate_minor_collection_allowance (void)
75 size_t new_major, new_heap_size, allowance_target, allowance;
77 if (!need_calculate_minor_collection_allowance)
80 SGEN_ASSERT (0, major_collector.have_swept (), "Can only calculate allowance if heap is swept");
82 new_major = major_collector.get_bytes_survived_last_sweep ();
83 new_heap_size = new_major + last_collection_los_memory_usage;
86 * We allow the heap to grow by one third its current size before we start the next
89 allowance_target = new_heap_size / 3;
91 allowance = MAX (allowance_target, MIN_MINOR_COLLECTION_ALLOWANCE);
93 if (new_heap_size + allowance > soft_heap_limit) {
94 if (new_heap_size > soft_heap_limit)
95 allowance = MIN_MINOR_COLLECTION_ALLOWANCE;
97 allowance = MAX (soft_heap_limit - new_heap_size, MIN_MINOR_COLLECTION_ALLOWANCE);
100 /* FIXME: Why is this here? */
101 if (major_collector.free_swept_blocks)
102 major_collector.free_swept_blocks (allowance);
104 major_collection_trigger_size = new_heap_size + allowance;
106 need_calculate_minor_collection_allowance = FALSE;
108 if (debug_print_allowance) {
109 SGEN_LOG (0, "Surviving sweep: %ld bytes (%ld major, %ld LOS)", (long)new_heap_size, (long)new_major, (long)last_collection_los_memory_usage);
110 SGEN_LOG (0, "Allowance: %ld bytes", (long)allowance);
111 SGEN_LOG (0, "Trigger size: %ld bytes", (long)major_collection_trigger_size);
116 sgen_need_major_collection (mword space_needed)
120 if (sgen_concurrent_collection_in_progress ())
123 /* FIXME: This is a cop-out. We should have some way of figuring this out. */
124 if (!major_collector.have_swept ())
127 if (space_needed > sgen_memgov_available_free_space ())
130 sgen_memgov_calculate_minor_collection_allowance ();
132 heap_size = major_collector.get_num_major_sections () * major_collector.section_size + los_memory_usage;
134 return heap_size > major_collection_trigger_size;
138 sgen_memgov_minor_collection_start (void)
143 sgen_memgov_minor_collection_end (void)
148 sgen_memgov_major_collection_start (void)
150 need_calculate_minor_collection_allowance = TRUE;
152 if (debug_print_allowance) {
153 SGEN_LOG (0, "Starting collection with heap size %ld bytes", (long)(major_collector.get_num_major_sections () * major_collector.section_size + los_memory_usage));
158 sgen_memgov_major_collection_end (gboolean forced)
160 last_collection_los_memory_usage = los_memory_usage;
163 sgen_get_major_collector ()->finish_sweeping ();
164 sgen_memgov_calculate_minor_collection_allowance ();
169 sgen_memgov_collection_start (int generation)
174 sgen_memgov_collection_end (int generation, GGTimingInfo* info, int info_count)
177 for (i = 0; i < info_count; ++i) {
178 if (info[i].generation != -1)
179 sgen_client_log_timing (&info [i], last_major_num_sections, last_los_memory_usage);
184 Global GC memory tracking.
185 This tracks the total usage of memory by the GC. This includes
186 managed and unmanaged memory.
190 prot_flags_for_activate (int activate)
192 unsigned long prot_flags = activate? MONO_MMAP_READ|MONO_MMAP_WRITE: MONO_MMAP_NONE;
193 return prot_flags | MONO_MMAP_PRIVATE | MONO_MMAP_ANON;
197 sgen_assert_memory_alloc (void *ptr, size_t requested_size, const char *assert_description)
199 if (ptr || !assert_description)
201 fprintf (stderr, "Error: Garbage collector could not allocate %zu bytes of memory for %s.\n", requested_size, assert_description);
206 * Allocate a big chunk of memory from the OS (usually 64KB to several megabytes).
207 * This must not require any lock.
210 sgen_alloc_os_memory (size_t size, SgenAllocFlags flags, const char *assert_description)
214 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
216 ptr = mono_valloc (0, size, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
217 sgen_assert_memory_alloc (ptr, size, assert_description);
219 SGEN_ATOMIC_ADD_P (total_alloc, size);
220 total_alloc_max = MAX (total_alloc_max, total_alloc);
225 /* size must be a power of 2 */
227 sgen_alloc_os_memory_aligned (size_t size, mword alignment, SgenAllocFlags flags, const char *assert_description)
231 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
233 ptr = mono_valloc_aligned (size, alignment, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
234 sgen_assert_memory_alloc (ptr, size, assert_description);
236 SGEN_ATOMIC_ADD_P (total_alloc, size);
237 total_alloc_max = MAX (total_alloc_max, total_alloc);
243 * Free the memory returned by sgen_alloc_os_memory (), returning it to the OS.
246 sgen_free_os_memory (void *addr, size_t size, SgenAllocFlags flags)
248 g_assert (!(flags & ~SGEN_ALLOC_HEAP));
250 mono_vfree (addr, size);
251 SGEN_ATOMIC_ADD_P (total_alloc, -(gssize)size);
252 total_alloc_max = MAX (total_alloc_max, total_alloc);
256 sgen_gc_get_total_heap_allocation (void)
264 This limit the max size of the heap. It takes into account
265 only memory actively in use to hold heap objects and not
266 for other parts of the GC.
269 sgen_memgov_available_free_space (void)
271 return max_heap_size - MIN (allocated_heap, max_heap_size);
275 sgen_memgov_release_space (mword size, int space)
277 SGEN_ATOMIC_ADD_P (allocated_heap, -(gssize)size);
281 sgen_memgov_try_alloc_space (mword size, int space)
283 if (sgen_memgov_available_free_space () < size) {
284 SGEN_ASSERT (4, !sgen_thread_pool_is_thread_pool_thread (mono_native_thread_id_get ()), "Memory shouldn't run out in worker thread");
288 SGEN_ATOMIC_ADD_P (allocated_heap, size);
289 sgen_client_total_allocated_heap_changed (allocated_heap);
294 sgen_memgov_init (size_t max_heap, size_t soft_limit, gboolean debug_allowance, double allowance_ratio, double save_target)
297 soft_heap_limit = soft_limit;
299 debug_print_allowance = debug_allowance;
300 major_collection_trigger_size = MIN_MINOR_COLLECTION_ALLOWANCE;
302 mono_counters_register ("Memgov alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_VARIABLE, &total_alloc);
303 mono_counters_register ("Memgov max alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_MONOTONIC, &total_alloc_max);
308 if (max_heap < soft_limit) {
309 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Setting to minimum.", "`max-heap-size` must be at least as large as `soft-heap-limit`.");
310 max_heap = soft_limit;
313 if (max_heap < sgen_nursery_size * 4) {
314 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`.");
315 max_heap = sgen_nursery_size * 4;
317 max_heap_size = max_heap - sgen_nursery_size;
320 default_allowance_nursery_size_ratio = allowance_ratio;
323 save_target_ratio = save_target;