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 major_pre_sweep_heap_size;
60 static mword major_start_heap_size;
62 static mword last_major_num_sections = 0;
63 static mword last_los_memory_usage = 0;
65 static gboolean need_calculate_minor_collection_allowance;
67 /* The size of the LOS after the last major collection, after sweeping. */
68 static mword last_collection_los_memory_usage = 0;
70 static mword sgen_memgov_available_free_space (void);
73 /* GC trigger heuristics. */
76 sgen_memgov_calculate_minor_collection_allowance (void)
78 size_t new_major, new_heap_size, allowance_target, allowance;
81 if (!need_calculate_minor_collection_allowance)
84 SGEN_ASSERT (0, major_collector.have_swept (), "Can only calculate allowance if heap is swept");
86 new_major = major_collector.get_bytes_survived_last_sweep ();
87 new_heap_size = new_major + last_collection_los_memory_usage;
90 * We allow the heap to grow by one third its current size before we start the next
93 allowance_target = new_heap_size * SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO;
95 allowance = MAX (allowance_target, MIN_MINOR_COLLECTION_ALLOWANCE);
98 * For the concurrent collector, we decrease the allowance relative to the memory
99 * growth during the M&S phase, survival rate of the collection and the allowance
102 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);
103 if (decrease > allowance)
104 decrease = allowance;
105 allowance -= decrease;
107 if (new_heap_size + allowance > soft_heap_limit) {
108 if (new_heap_size > soft_heap_limit)
109 allowance = MIN_MINOR_COLLECTION_ALLOWANCE;
111 allowance = MAX (soft_heap_limit - new_heap_size, MIN_MINOR_COLLECTION_ALLOWANCE);
114 /* FIXME: Why is this here? */
115 if (major_collector.free_swept_blocks)
116 major_collector.free_swept_blocks (allowance);
118 major_collection_trigger_size = new_heap_size + allowance;
120 need_calculate_minor_collection_allowance = FALSE;
122 if (debug_print_allowance) {
123 SGEN_LOG (0, "Surviving sweep: %ld bytes (%ld major, %ld LOS)", (long)new_heap_size, (long)new_major, (long)last_collection_los_memory_usage);
124 SGEN_LOG (0, "Allowance: %ld bytes", (long)allowance);
125 SGEN_LOG (0, "Trigger size: %ld bytes", (long)major_collection_trigger_size);
132 return major_collector.get_num_major_sections () * major_collector.section_size + los_memory_usage;
136 sgen_need_major_collection (mword space_needed)
140 if (sgen_concurrent_collection_in_progress ()) {
141 heap_size = get_heap_size ();
143 if (heap_size <= major_collection_trigger_size)
147 * The more the heap grows, the more we need to decrease the allowance above,
148 * in order to have similar trigger sizes as the synchronous collector.
149 * If the heap grows so much that we would need to have a negative allowance,
150 * we force the finishing of the collection, to avoid increased memory usage.
152 if ((heap_size - major_start_heap_size) > major_start_heap_size * SGEN_DEFAULT_ALLOWANCE_HEAP_SIZE_RATIO)
157 /* FIXME: This is a cop-out. We should have some way of figuring this out. */
158 if (!major_collector.have_swept ())
161 if (space_needed > sgen_memgov_available_free_space ())
164 sgen_memgov_calculate_minor_collection_allowance ();
166 heap_size = get_heap_size ();
168 return heap_size > major_collection_trigger_size;
172 sgen_memgov_minor_collection_start (void)
177 sgen_memgov_minor_collection_end (void)
182 sgen_memgov_major_pre_sweep (void)
184 if (sgen_concurrent_collection_in_progress ()) {
185 major_pre_sweep_heap_size = get_heap_size ();
187 /* We decrease the allowance only in the concurrent case */
188 major_pre_sweep_heap_size = major_start_heap_size;
193 sgen_memgov_major_post_sweep (void)
195 mword num_major_sections = major_collector.get_num_major_sections ();
197 mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "GC_MAJOR_SWEEP: major %dK/%dK",
198 num_major_sections * major_collector.section_size / 1024,
199 last_major_num_sections * major_collector.section_size / 1024);
200 last_major_num_sections = num_major_sections;
204 sgen_memgov_major_collection_start (void)
206 need_calculate_minor_collection_allowance = TRUE;
207 major_start_heap_size = get_heap_size ();
209 if (debug_print_allowance) {
210 SGEN_LOG (0, "Starting collection with heap size %ld bytes", (long)major_start_heap_size);
215 sgen_memgov_major_collection_end (gboolean forced)
217 last_collection_los_memory_usage = los_memory_usage;
220 sgen_get_major_collector ()->finish_sweeping ();
221 sgen_memgov_calculate_minor_collection_allowance ();
226 sgen_memgov_collection_start (int generation)
231 sgen_memgov_collection_end (int generation, GGTimingInfo* info, int info_count)
234 for (i = 0; i < info_count; ++i) {
235 if (info[i].generation != -1)
236 sgen_client_log_timing (&info [i], last_major_num_sections, last_los_memory_usage);
238 last_los_memory_usage = los_memory_usage;
242 Global GC memory tracking.
243 This tracks the total usage of memory by the GC. This includes
244 managed and unmanaged memory.
248 prot_flags_for_activate (int activate)
250 unsigned long prot_flags = activate? MONO_MMAP_READ|MONO_MMAP_WRITE: MONO_MMAP_NONE;
251 return prot_flags | MONO_MMAP_PRIVATE | MONO_MMAP_ANON;
255 sgen_assert_memory_alloc (void *ptr, size_t requested_size, const char *assert_description)
257 if (ptr || !assert_description)
259 fprintf (stderr, "Error: Garbage collector could not allocate %zu bytes of memory for %s.\n", requested_size, assert_description);
264 * Allocate a big chunk of memory from the OS (usually 64KB to several megabytes).
265 * This must not require any lock.
268 sgen_alloc_os_memory (size_t size, SgenAllocFlags flags, const char *assert_description)
272 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
274 ptr = mono_valloc (0, size, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
275 sgen_assert_memory_alloc (ptr, size, assert_description);
277 SGEN_ATOMIC_ADD_P (total_alloc, size);
278 total_alloc_max = MAX (total_alloc_max, total_alloc);
283 /* size must be a power of 2 */
285 sgen_alloc_os_memory_aligned (size_t size, mword alignment, SgenAllocFlags flags, const char *assert_description)
289 g_assert (!(flags & ~(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE)));
291 ptr = mono_valloc_aligned (size, alignment, prot_flags_for_activate (flags & SGEN_ALLOC_ACTIVATE));
292 sgen_assert_memory_alloc (ptr, size, assert_description);
294 SGEN_ATOMIC_ADD_P (total_alloc, size);
295 total_alloc_max = MAX (total_alloc_max, total_alloc);
301 * Free the memory returned by sgen_alloc_os_memory (), returning it to the OS.
304 sgen_free_os_memory (void *addr, size_t size, SgenAllocFlags flags)
306 g_assert (!(flags & ~SGEN_ALLOC_HEAP));
308 mono_vfree (addr, size);
309 SGEN_ATOMIC_ADD_P (total_alloc, -(gssize)size);
310 total_alloc_max = MAX (total_alloc_max, total_alloc);
314 sgen_gc_get_total_heap_allocation (void)
322 This limit the max size of the heap. It takes into account
323 only memory actively in use to hold heap objects and not
324 for other parts of the GC.
327 sgen_memgov_available_free_space (void)
329 return max_heap_size - MIN (allocated_heap, max_heap_size);
333 sgen_memgov_release_space (mword size, int space)
335 SGEN_ATOMIC_ADD_P (allocated_heap, -(gssize)size);
339 sgen_memgov_try_alloc_space (mword size, int space)
341 if (sgen_memgov_available_free_space () < size) {
342 SGEN_ASSERT (4, !sgen_thread_pool_is_thread_pool_thread (mono_native_thread_id_get ()), "Memory shouldn't run out in worker thread");
346 SGEN_ATOMIC_ADD_P (allocated_heap, size);
347 sgen_client_total_allocated_heap_changed (allocated_heap);
352 sgen_memgov_init (size_t max_heap, size_t soft_limit, gboolean debug_allowance, double allowance_ratio, double save_target)
355 soft_heap_limit = soft_limit;
357 debug_print_allowance = debug_allowance;
358 major_collection_trigger_size = MIN_MINOR_COLLECTION_ALLOWANCE;
360 mono_counters_register ("Memgov alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_VARIABLE, &total_alloc);
361 mono_counters_register ("Memgov max alloc", MONO_COUNTER_GC | MONO_COUNTER_WORD | MONO_COUNTER_BYTES | MONO_COUNTER_MONOTONIC, &total_alloc_max);
366 if (max_heap < soft_limit) {
367 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Setting to minimum.", "`max-heap-size` must be at least as large as `soft-heap-limit`.");
368 max_heap = soft_limit;
371 if (max_heap < sgen_nursery_size * 4) {
372 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`.");
373 max_heap = sgen_nursery_size * 4;
375 max_heap_size = max_heap - sgen_nursery_size;
378 default_allowance_nursery_size_ratio = allowance_ratio;
381 save_target_ratio = save_target;