1 /* GLIB sliced memory - fast concurrent memory chunk allocator
2 * Copyright (C) 2005 Tim Janik
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
22 #include "glibconfig.h"
24 #if defined HAVE_POSIX_MEMALIGN && defined POSIX_MEMALIGN_WITH_COMPLIANT_ALLOCS
25 # define HAVE_COMPLIANT_POSIX_MEMALIGN 1
28 #if defined(HAVE_COMPLIANT_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE)
29 #define _XOPEN_SOURCE 600 /* posix_memalign() */
31 #include <stdlib.h> /* posix_memalign() */
36 #include <unistd.h> /* sysconf() */
43 #include <stdio.h> /* fputs/fprintf */
48 #include "gmem.h" /* gslice.h */
49 #include "gstrfuncs.h"
51 #include "gtestutils.h"
53 #include "glib_trace.h"
54 #include "glib-ctor.h"
56 /* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
57 * allocator and magazine extensions as outlined in:
58 * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
59 * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
60 * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
61 * slab allocator to many cpu's and arbitrary resources.
62 * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
64 * - the thread magazines. for each (aligned) chunk size, a magazine (a list)
65 * of recently freed and soon to be allocated chunks is maintained per thread.
66 * this way, most alloc/free requests can be quickly satisfied from per-thread
67 * free lists which only require one g_private_get() call to retrive the
69 * - the magazine cache. allocating and freeing chunks to/from threads only
70 * occours at magazine sizes from a global depot of magazines. the depot
71 * maintaines a 15 second working set of allocated magazines, so full
72 * magazines are not allocated and released too often.
73 * the chunk size dependent magazine sizes automatically adapt (within limits,
74 * see [3]) to lock contention to properly scale performance across a variety
76 * - the slab allocator. this allocator allocates slabs (blocks of memory) close
77 * to the system page size or multiples thereof which have to be page aligned.
78 * the blocks are divided into smaller chunks which are used to satisfy
79 * allocations from the upper layers. the space provided by the reminder of
80 * the chunk size division is used for cache colorization (random distribution
81 * of chunk addresses) to improve processor cache utilization. multiple slabs
82 * with the same chunk size are kept in a partially sorted ring to allow O(1)
83 * freeing and allocation of chunks (as long as the allocation of an entirely
84 * new slab can be avoided).
85 * - the page allocator. on most modern systems, posix_memalign(3) or
86 * memalign(3) should be available, so this is used to allocate blocks with
87 * system page size based alignments and sizes or multiples thereof.
88 * if no memalign variant is provided, valloc() is used instead and
89 * block sizes are limited to the system page size (no multiples thereof).
90 * as a fallback, on system without even valloc(), a malloc(3)-based page
91 * allocator with alloc-only behaviour is used.
94 * [1] some systems memalign(3) implementations may rely on boundary tagging for
95 * the handed out memory chunks. to avoid excessive page-wise fragmentation,
96 * we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
97 * specified in NATIVE_MALLOC_PADDING.
98 * [2] using the slab allocator alone already provides for a fast and efficient
99 * allocator, it doesn't properly scale beyond single-threaded uses though.
100 * also, the slab allocator implements eager free(3)-ing, i.e. does not
101 * provide any form of caching or working set maintenance. so if used alone,
102 * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
103 * at certain thresholds.
104 * [3] magazine sizes are bound by an implementation specific minimum size and
105 * a chunk size specific maximum to limit magazine storage sizes to roughly
107 * [4] allocating ca. 8 chunks per block/page keeps a good balance between
108 * external and internal fragmentation (<= 12.5%). [Bonwick94]
111 /* --- macros and constants --- */
112 #define LARGEALIGNMENT (256)
113 #define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
114 #define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
115 #define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
116 #define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
117 #define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
118 #define MIN_MAGAZINE_SIZE (4)
119 #define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
120 #define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
121 #define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
122 #define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
123 #define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
124 #define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
126 /* optimized version of ALIGN (size, P2ALIGNMENT) */
127 #if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
128 #define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
129 #elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
130 #define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
132 #define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
135 /* special helpers to avoid gmessage.c dependency */
136 static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
137 #define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
139 /* --- structures --- */
140 typedef struct _ChunkLink ChunkLink;
141 typedef struct _SlabInfo SlabInfo;
142 typedef struct _CachedMagazine CachedMagazine;
150 SlabInfo *next, *prev;
154 gsize count; /* approximative chunks list length */
157 Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */
158 Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */
161 gboolean always_malloc;
162 gboolean bypass_magazines;
163 gboolean debug_blocks;
164 gsize working_set_msecs;
165 guint color_increment;
168 /* const after initialization */
169 gsize min_page_size, max_page_size;
171 gsize max_slab_chunk_size_for_magazine_cache;
173 GMutex magazine_mutex;
174 ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */
175 guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */
181 SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */
185 /* --- g-slice prototypes --- */
186 static gpointer slab_allocator_alloc_chunk (gsize chunk_size);
187 static void slab_allocator_free_chunk (gsize chunk_size,
189 static void private_thread_memory_cleanup (gpointer data);
190 static gpointer allocator_memalign (gsize alignment,
192 static void allocator_memfree (gsize memsize,
194 static inline void magazine_cache_update_stamp (void);
195 static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
198 /* --- g-slice memory checker --- */
199 static void smc_notify_alloc (void *pointer,
201 static int smc_notify_free (void *pointer,
204 /* --- variables --- */
205 static GPrivate private_thread_memory = G_PRIVATE_INIT (private_thread_memory_cleanup);
206 static gsize sys_page_size = 0;
207 static Allocator allocator[1] = { { 0, }, };
208 static SliceConfig slice_config = {
209 FALSE, /* always_malloc */
210 FALSE, /* bypass_magazines */
211 FALSE, /* debug_blocks */
212 15 * 1000, /* working_set_msecs */
213 1, /* color increment, alt: 0x7fffffff */
215 static GMutex smc_tree_mutex = G_MUTEX_INIT; /* mutex for G_SLICE=debug-blocks */
217 /* --- auxiliary funcitons --- */
219 g_slice_set_config (GSliceConfig ckey,
222 g_return_if_fail (sys_page_size == 0);
225 case G_SLICE_CONFIG_ALWAYS_MALLOC:
226 slice_config.always_malloc = value != 0;
228 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
229 slice_config.bypass_magazines = value != 0;
231 case G_SLICE_CONFIG_WORKING_SET_MSECS:
232 slice_config.working_set_msecs = value;
234 case G_SLICE_CONFIG_COLOR_INCREMENT:
235 slice_config.color_increment = value;
241 g_slice_get_config (GSliceConfig ckey)
245 case G_SLICE_CONFIG_ALWAYS_MALLOC:
246 return slice_config.always_malloc;
247 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
248 return slice_config.bypass_magazines;
249 case G_SLICE_CONFIG_WORKING_SET_MSECS:
250 return slice_config.working_set_msecs;
251 case G_SLICE_CONFIG_CHUNK_SIZES:
252 return MAX_SLAB_INDEX (allocator);
253 case G_SLICE_CONFIG_COLOR_INCREMENT:
254 return slice_config.color_increment;
261 g_slice_get_config_state (GSliceConfig ckey,
266 g_return_val_if_fail (n_values != NULL, NULL);
271 case G_SLICE_CONFIG_CONTENTION_COUNTER:
272 array[i++] = SLAB_CHUNK_SIZE (allocator, address);
273 array[i++] = allocator->contention_counters[address];
274 array[i++] = allocator_get_magazine_threshold (allocator, address);
276 return g_memdup (array, sizeof (array[0]) * *n_values);
283 slice_config_init (SliceConfig *config)
285 /* don't use g_malloc/g_message here */
287 const gchar *val = _g_getenv_nomalloc ("G_SLICE", buffer);
288 const GDebugKey keys[] = {
289 { "always-malloc", 1 << 0 },
290 { "debug-blocks", 1 << 1 },
292 gint flags = !val ? 0 : g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
293 *config = slice_config;
294 if (flags & (1 << 0)) /* always-malloc */
295 config->always_malloc = TRUE;
296 if (flags & (1 << 1)) /* debug-blocks */
297 config->debug_blocks = TRUE;
300 GLIB_CTOR (g_slice_init_nomessage)
302 /* we may not use g_error() or friends here */
303 mem_assert (sys_page_size == 0);
304 mem_assert (MIN_MAGAZINE_SIZE >= 4);
308 SYSTEM_INFO system_info;
309 GetSystemInfo (&system_info);
310 sys_page_size = system_info.dwPageSize;
313 sys_page_size = sysconf (_SC_PAGESIZE); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */
315 mem_assert (sys_page_size >= 2 * LARGEALIGNMENT);
316 mem_assert ((sys_page_size & (sys_page_size - 1)) == 0);
317 slice_config_init (&allocator->config);
318 allocator->min_page_size = sys_page_size;
319 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN
320 /* allow allocation of pages up to 8KB (with 8KB alignment).
321 * this is useful because many medium to large sized structures
322 * fit less than 8 times (see [4]) into 4KB pages.
323 * we allow very small page sizes here, to reduce wastage in
324 * threads if only small allocations are required (this does
325 * bear the risk of incresing allocation times and fragmentation
328 allocator->min_page_size = MAX (allocator->min_page_size, 4096);
329 allocator->max_page_size = MAX (allocator->min_page_size, 8192);
330 allocator->min_page_size = MIN (allocator->min_page_size, 128);
332 /* we can only align to system page size */
333 allocator->max_page_size = sys_page_size;
335 if (allocator->config.always_malloc)
337 allocator->contention_counters = NULL;
338 allocator->magazines = NULL;
339 allocator->slab_stack = NULL;
343 allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator));
344 allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator));
345 allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
348 g_mutex_init (&allocator->magazine_mutex);
349 allocator->mutex_counter = 0;
350 allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
351 allocator->last_stamp = 0;
352 g_mutex_init (&allocator->slab_mutex);
353 allocator->color_accu = 0;
354 magazine_cache_update_stamp();
355 /* values cached for performance reasons */
356 allocator->max_slab_chunk_size_for_magazine_cache = MAX_SLAB_CHUNK_SIZE (allocator);
357 if (allocator->config.always_malloc || allocator->config.bypass_magazines)
358 allocator->max_slab_chunk_size_for_magazine_cache = 0; /* non-optimized cases */
359 /* at this point, g_mem_gc_friendly() should be initialized, this
360 * should have been accomplished by the above g_malloc/g_new calls
365 allocator_categorize (gsize aligned_chunk_size)
367 GLIB_ENSURE_CTOR (g_slice_init_nomessage);
369 /* speed up the likely path */
370 if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
371 return 1; /* use magazine cache */
373 if (!allocator->config.always_malloc &&
374 aligned_chunk_size &&
375 aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
377 if (allocator->config.bypass_magazines)
378 return 2; /* use slab allocator, see [2] */
379 return 1; /* use magazine cache */
381 return 0; /* use malloc() */
385 g_mutex_lock_a (GMutex *mutex,
386 guint *contention_counter)
388 gboolean contention = FALSE;
389 if (!g_mutex_trylock (mutex))
391 g_mutex_lock (mutex);
396 allocator->mutex_counter++;
397 if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
399 allocator->mutex_counter = 0;
400 *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
403 else /* !contention */
405 allocator->mutex_counter--;
406 if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
408 allocator->mutex_counter = 0;
409 *contention_counter = MAX (*contention_counter, 1) - 1;
414 static inline ThreadMemory*
415 thread_memory_from_self (void)
417 ThreadMemory *tmem = g_private_get (&private_thread_memory);
418 if (G_UNLIKELY (!tmem))
420 const guint n_magazines = MAX_SLAB_INDEX (allocator);
421 tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
422 tmem->magazine1 = (Magazine*) (tmem + 1);
423 tmem->magazine2 = &tmem->magazine1[n_magazines];
424 g_private_set (&private_thread_memory, tmem);
429 static inline ChunkLink*
430 magazine_chain_pop_head (ChunkLink **magazine_chunks)
432 /* magazine chains are linked via ChunkLink->next.
433 * each ChunkLink->data of the toplevel chain may point to a subchain,
434 * linked via ChunkLink->next. ChunkLink->data of the subchains just
435 * contains uninitialized junk.
437 ChunkLink *chunk = (*magazine_chunks)->data;
438 if (G_UNLIKELY (chunk))
440 /* allocating from freed list */
441 (*magazine_chunks)->data = chunk->next;
445 chunk = *magazine_chunks;
446 *magazine_chunks = chunk->next;
451 #if 0 /* useful for debugging */
453 magazine_count (ChunkLink *head)
460 ChunkLink *child = head->data;
462 for (child = head->data; child; child = child->next)
471 allocator_get_magazine_threshold (Allocator *allocator,
474 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
475 * which is required by the implementation. also, for moderately sized chunks
476 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
477 * of chunks available per page/2 to avoid excessive traffic in the magazine
478 * cache for small to medium sized structures.
479 * the upper bound of the magazine size is effectively provided by
480 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
481 * the content of a single magazine doesn't exceed ca. 16KB.
483 gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
484 guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
485 guint contention_counter = allocator->contention_counters[ix];
486 if (G_UNLIKELY (contention_counter)) /* single CPU bias */
488 /* adapt contention counter thresholds to chunk sizes */
489 contention_counter = contention_counter * 64 / chunk_size;
490 threshold = MAX (threshold, contention_counter);
495 /* --- magazine cache --- */
497 magazine_cache_update_stamp (void)
499 if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
502 g_get_current_time (&tv);
503 allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000; /* milli seconds */
504 allocator->stamp_counter = 0;
507 allocator->stamp_counter++;
510 static inline ChunkLink*
511 magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
517 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
518 /* ensure a magazine with at least 4 unused data pointers */
519 chunk1 = magazine_chain_pop_head (&magazine_chunks);
520 chunk2 = magazine_chain_pop_head (&magazine_chunks);
521 chunk3 = magazine_chain_pop_head (&magazine_chunks);
522 chunk4 = magazine_chain_pop_head (&magazine_chunks);
523 chunk4->next = magazine_chunks;
524 chunk3->next = chunk4;
525 chunk2->next = chunk3;
526 chunk1->next = chunk2;
530 /* access the first 3 fields of a specially prepared magazine chain */
531 #define magazine_chain_prev(mc) ((mc)->data)
532 #define magazine_chain_stamp(mc) ((mc)->next->data)
533 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
534 #define magazine_chain_next(mc) ((mc)->next->next->data)
535 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
538 magazine_cache_trim (Allocator *allocator,
542 /* g_mutex_lock (allocator->mutex); done by caller */
543 /* trim magazine cache from tail */
544 ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
545 ChunkLink *trash = NULL;
546 while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator->config.working_set_msecs)
549 ChunkLink *prev = magazine_chain_prev (current);
550 ChunkLink *next = magazine_chain_next (current);
551 magazine_chain_next (prev) = next;
552 magazine_chain_prev (next) = prev;
553 /* clear special fields, put on trash stack */
554 magazine_chain_next (current) = NULL;
555 magazine_chain_count (current) = NULL;
556 magazine_chain_stamp (current) = NULL;
557 magazine_chain_prev (current) = trash;
559 /* fixup list head if required */
560 if (current == allocator->magazines[ix])
562 allocator->magazines[ix] = NULL;
567 g_mutex_unlock (&allocator->magazine_mutex);
571 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
572 g_mutex_lock (&allocator->slab_mutex);
576 trash = magazine_chain_prev (current);
577 magazine_chain_prev (current) = NULL; /* clear special field */
580 ChunkLink *chunk = magazine_chain_pop_head (¤t);
581 slab_allocator_free_chunk (chunk_size, chunk);
584 g_mutex_unlock (&allocator->slab_mutex);
589 magazine_cache_push_magazine (guint ix,
590 ChunkLink *magazine_chunks,
591 gsize count) /* must be >= MIN_MAGAZINE_SIZE */
593 ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
594 ChunkLink *next, *prev;
595 g_mutex_lock (&allocator->magazine_mutex);
596 /* add magazine at head */
597 next = allocator->magazines[ix];
599 prev = magazine_chain_prev (next);
601 next = prev = current;
602 magazine_chain_next (prev) = current;
603 magazine_chain_prev (next) = current;
604 magazine_chain_prev (current) = prev;
605 magazine_chain_next (current) = next;
606 magazine_chain_count (current) = (gpointer) count;
608 magazine_cache_update_stamp();
609 magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
610 allocator->magazines[ix] = current;
611 /* free old magazines beyond a certain threshold */
612 magazine_cache_trim (allocator, ix, allocator->last_stamp);
613 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
617 magazine_cache_pop_magazine (guint ix,
620 g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]);
621 if (!allocator->magazines[ix])
623 guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
624 gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
625 ChunkLink *chunk, *head;
626 g_mutex_unlock (&allocator->magazine_mutex);
627 g_mutex_lock (&allocator->slab_mutex);
628 head = slab_allocator_alloc_chunk (chunk_size);
631 for (i = 1; i < magazine_threshold; i++)
633 chunk->next = slab_allocator_alloc_chunk (chunk_size);
638 g_mutex_unlock (&allocator->slab_mutex);
644 ChunkLink *current = allocator->magazines[ix];
645 ChunkLink *prev = magazine_chain_prev (current);
646 ChunkLink *next = magazine_chain_next (current);
648 magazine_chain_next (prev) = next;
649 magazine_chain_prev (next) = prev;
650 allocator->magazines[ix] = next == current ? NULL : next;
651 g_mutex_unlock (&allocator->magazine_mutex);
652 /* clear special fields and hand out */
653 *countp = (gsize) magazine_chain_count (current);
654 magazine_chain_prev (current) = NULL;
655 magazine_chain_next (current) = NULL;
656 magazine_chain_count (current) = NULL;
657 magazine_chain_stamp (current) = NULL;
662 /* --- thread magazines --- */
664 private_thread_memory_cleanup (gpointer data)
666 ThreadMemory *tmem = data;
667 const guint n_magazines = MAX_SLAB_INDEX (allocator);
669 for (ix = 0; ix < n_magazines; ix++)
673 mags[0] = &tmem->magazine1[ix];
674 mags[1] = &tmem->magazine2[ix];
675 for (j = 0; j < 2; j++)
677 Magazine *mag = mags[j];
678 if (mag->count >= MIN_MAGAZINE_SIZE)
679 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
682 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
683 g_mutex_lock (&allocator->slab_mutex);
686 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
687 slab_allocator_free_chunk (chunk_size, chunk);
689 g_mutex_unlock (&allocator->slab_mutex);
697 thread_memory_magazine1_reload (ThreadMemory *tmem,
700 Magazine *mag = &tmem->magazine1[ix];
701 mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
703 mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
707 thread_memory_magazine2_unload (ThreadMemory *tmem,
710 Magazine *mag = &tmem->magazine2[ix];
711 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
717 thread_memory_swap_magazines (ThreadMemory *tmem,
720 Magazine xmag = tmem->magazine1[ix];
721 tmem->magazine1[ix] = tmem->magazine2[ix];
722 tmem->magazine2[ix] = xmag;
725 static inline gboolean
726 thread_memory_magazine1_is_empty (ThreadMemory *tmem,
729 return tmem->magazine1[ix].chunks == NULL;
732 static inline gboolean
733 thread_memory_magazine2_is_full (ThreadMemory *tmem,
736 return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
739 static inline gpointer
740 thread_memory_magazine1_alloc (ThreadMemory *tmem,
743 Magazine *mag = &tmem->magazine1[ix];
744 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
745 if (G_LIKELY (mag->count > 0))
751 thread_memory_magazine2_free (ThreadMemory *tmem,
755 Magazine *mag = &tmem->magazine2[ix];
756 ChunkLink *chunk = mem;
758 chunk->next = mag->chunks;
763 /* --- API functions --- */
765 g_slice_alloc (gsize mem_size)
770 chunk_size = P2ALIGN (mem_size);
771 acat = allocator_categorize (chunk_size);
772 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
774 ThreadMemory *tmem = thread_memory_from_self();
775 guint ix = SLAB_INDEX (allocator, chunk_size);
776 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
778 thread_memory_swap_magazines (tmem, ix);
779 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
780 thread_memory_magazine1_reload (tmem, ix);
782 mem = thread_memory_magazine1_alloc (tmem, ix);
784 else if (acat == 2) /* allocate through slab allocator */
786 g_mutex_lock (&allocator->slab_mutex);
787 mem = slab_allocator_alloc_chunk (chunk_size);
788 g_mutex_unlock (&allocator->slab_mutex);
790 else /* delegate to system malloc */
791 mem = g_malloc (mem_size);
792 if (G_UNLIKELY (allocator->config.debug_blocks))
793 smc_notify_alloc (mem, mem_size);
795 TRACE (GLIB_SLICE_ALLOC((void*)mem, mem_size));
801 g_slice_alloc0 (gsize mem_size)
803 gpointer mem = g_slice_alloc (mem_size);
805 memset (mem, 0, mem_size);
810 g_slice_copy (gsize mem_size,
811 gconstpointer mem_block)
813 gpointer mem = g_slice_alloc (mem_size);
815 memcpy (mem, mem_block, mem_size);
820 g_slice_free1 (gsize mem_size,
823 gsize chunk_size = P2ALIGN (mem_size);
824 guint acat = allocator_categorize (chunk_size);
825 if (G_UNLIKELY (!mem_block))
827 if (G_UNLIKELY (allocator->config.debug_blocks) &&
828 !smc_notify_free (mem_block, mem_size))
830 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
832 ThreadMemory *tmem = thread_memory_from_self();
833 guint ix = SLAB_INDEX (allocator, chunk_size);
834 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
836 thread_memory_swap_magazines (tmem, ix);
837 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
838 thread_memory_magazine2_unload (tmem, ix);
840 if (G_UNLIKELY (g_mem_gc_friendly))
841 memset (mem_block, 0, chunk_size);
842 thread_memory_magazine2_free (tmem, ix, mem_block);
844 else if (acat == 2) /* allocate through slab allocator */
846 if (G_UNLIKELY (g_mem_gc_friendly))
847 memset (mem_block, 0, chunk_size);
848 g_mutex_lock (&allocator->slab_mutex);
849 slab_allocator_free_chunk (chunk_size, mem_block);
850 g_mutex_unlock (&allocator->slab_mutex);
852 else /* delegate to system malloc */
854 if (G_UNLIKELY (g_mem_gc_friendly))
855 memset (mem_block, 0, mem_size);
858 TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size));
862 g_slice_free_chain_with_offset (gsize mem_size,
866 gpointer slice = mem_chain;
867 /* while the thread magazines and the magazine cache are implemented so that
868 * they can easily be extended to allow for free lists containing more free
869 * lists for the first level nodes, which would allow O(1) freeing in this
870 * function, the benefit of such an extension is questionable, because:
871 * - the magazine size counts will become mere lower bounds which confuses
872 * the code adapting to lock contention;
873 * - freeing a single node to the thread magazines is very fast, so this
874 * O(list_length) operation is multiplied by a fairly small factor;
875 * - memory usage histograms on larger applications seem to indicate that
876 * the amount of released multi node lists is negligible in comparison
877 * to single node releases.
878 * - the major performance bottle neck, namely g_private_get() or
879 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
880 * inner loop for freeing chained slices.
882 gsize chunk_size = P2ALIGN (mem_size);
883 guint acat = allocator_categorize (chunk_size);
884 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
886 ThreadMemory *tmem = thread_memory_from_self();
887 guint ix = SLAB_INDEX (allocator, chunk_size);
890 guint8 *current = slice;
891 slice = *(gpointer*) (current + next_offset);
892 if (G_UNLIKELY (allocator->config.debug_blocks) &&
893 !smc_notify_free (current, mem_size))
895 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
897 thread_memory_swap_magazines (tmem, ix);
898 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
899 thread_memory_magazine2_unload (tmem, ix);
901 if (G_UNLIKELY (g_mem_gc_friendly))
902 memset (current, 0, chunk_size);
903 thread_memory_magazine2_free (tmem, ix, current);
906 else if (acat == 2) /* allocate through slab allocator */
908 g_mutex_lock (&allocator->slab_mutex);
911 guint8 *current = slice;
912 slice = *(gpointer*) (current + next_offset);
913 if (G_UNLIKELY (allocator->config.debug_blocks) &&
914 !smc_notify_free (current, mem_size))
916 if (G_UNLIKELY (g_mem_gc_friendly))
917 memset (current, 0, chunk_size);
918 slab_allocator_free_chunk (chunk_size, current);
920 g_mutex_unlock (&allocator->slab_mutex);
922 else /* delegate to system malloc */
925 guint8 *current = slice;
926 slice = *(gpointer*) (current + next_offset);
927 if (G_UNLIKELY (allocator->config.debug_blocks) &&
928 !smc_notify_free (current, mem_size))
930 if (G_UNLIKELY (g_mem_gc_friendly))
931 memset (current, 0, mem_size);
936 /* --- single page allocator --- */
938 allocator_slab_stack_push (Allocator *allocator,
942 /* insert slab at slab ring head */
943 if (!allocator->slab_stack[ix])
950 SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
956 allocator->slab_stack[ix] = sinfo;
960 allocator_aligned_page_size (Allocator *allocator,
963 gsize val = 1 << g_bit_storage (n_bytes - 1);
964 val = MAX (val, allocator->min_page_size);
969 allocator_add_slab (Allocator *allocator,
975 gsize addr, padding, n_chunks, color = 0;
976 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
977 /* allocate 1 page for the chunks and the slab */
978 gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
979 guint8 *mem = aligned_memory;
983 const gchar *syserr = "unknown error";
985 syserr = strerror (errno);
987 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
988 (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
990 /* mask page address */
991 addr = ((gsize) mem / page_size) * page_size;
992 /* assert alignment */
993 mem_assert (aligned_memory == (gpointer) addr);
994 /* basic slab info setup */
995 sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
996 sinfo->n_allocated = 0;
997 sinfo->chunks = NULL;
998 /* figure cache colorization */
999 n_chunks = ((guint8*) sinfo - mem) / chunk_size;
1000 padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
1003 color = (allocator->color_accu * P2ALIGNMENT) % padding;
1004 allocator->color_accu += allocator->config.color_increment;
1006 /* add chunks to free list */
1007 chunk = (ChunkLink*) (mem + color);
1008 sinfo->chunks = chunk;
1009 for (i = 0; i < n_chunks - 1; i++)
1011 chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
1012 chunk = chunk->next;
1014 chunk->next = NULL; /* last chunk */
1015 /* add slab to slab ring */
1016 allocator_slab_stack_push (allocator, ix, sinfo);
1020 slab_allocator_alloc_chunk (gsize chunk_size)
1023 guint ix = SLAB_INDEX (allocator, chunk_size);
1024 /* ensure non-empty slab */
1025 if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
1026 allocator_add_slab (allocator, ix, chunk_size);
1027 /* allocate chunk */
1028 chunk = allocator->slab_stack[ix]->chunks;
1029 allocator->slab_stack[ix]->chunks = chunk->next;
1030 allocator->slab_stack[ix]->n_allocated++;
1031 /* rotate empty slabs */
1032 if (!allocator->slab_stack[ix]->chunks)
1033 allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
1038 slab_allocator_free_chunk (gsize chunk_size,
1043 guint ix = SLAB_INDEX (allocator, chunk_size);
1044 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1045 gsize addr = ((gsize) mem / page_size) * page_size;
1046 /* mask page address */
1047 guint8 *page = (guint8*) addr;
1048 SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
1049 /* assert valid chunk count */
1050 mem_assert (sinfo->n_allocated > 0);
1051 /* add chunk to free list */
1052 was_empty = sinfo->chunks == NULL;
1053 chunk = (ChunkLink*) mem;
1054 chunk->next = sinfo->chunks;
1055 sinfo->chunks = chunk;
1056 sinfo->n_allocated--;
1057 /* keep slab ring partially sorted, empty slabs at end */
1061 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1064 if (allocator->slab_stack[ix] == sinfo)
1065 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1066 /* insert slab at head */
1067 allocator_slab_stack_push (allocator, ix, sinfo);
1069 /* eagerly free complete unused slabs */
1070 if (!sinfo->n_allocated)
1073 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1076 if (allocator->slab_stack[ix] == sinfo)
1077 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1079 allocator_memfree (page_size, page);
1083 /* --- memalign implementation --- */
1084 #ifdef HAVE_MALLOC_H
1085 #include <malloc.h> /* memalign() */
1089 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1090 * define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
1091 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1092 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1093 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1096 #if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1097 static GTrashStack *compat_valloc_trash = NULL;
1101 allocator_memalign (gsize alignment,
1104 gpointer aligned_memory = NULL;
1106 #if HAVE_COMPLIANT_POSIX_MEMALIGN
1107 err = posix_memalign (&aligned_memory, alignment, memsize);
1110 aligned_memory = memalign (alignment, memsize);
1114 aligned_memory = valloc (memsize);
1117 /* simplistic non-freeing page allocator */
1118 mem_assert (alignment == sys_page_size);
1119 mem_assert (memsize <= sys_page_size);
1120 if (!compat_valloc_trash)
1122 const guint n_pages = 16;
1123 guint8 *mem = malloc (n_pages * sys_page_size);
1128 guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
1130 i--; /* mem wasn't page aligned */
1132 g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
1135 aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
1137 if (!aligned_memory)
1139 return aligned_memory;
1143 allocator_memfree (gsize memsize,
1146 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1149 mem_assert (memsize <= sys_page_size);
1150 g_trash_stack_push (&compat_valloc_trash, mem);
1155 mem_error (const char *format,
1160 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1161 fputs ("\n***MEMORY-ERROR***: ", stderr);
1162 pname = g_get_prgname();
1163 fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid());
1164 va_start (args, format);
1165 vfprintf (stderr, format, args);
1167 fputs ("\n", stderr);
1172 /* --- g-slice memory checker tree --- */
1173 typedef size_t SmcKType; /* key type */
1174 typedef size_t SmcVType; /* value type */
1179 static void smc_tree_insert (SmcKType key,
1181 static gboolean smc_tree_lookup (SmcKType key,
1183 static gboolean smc_tree_remove (SmcKType key);
1186 /* --- g-slice memory checker implementation --- */
1188 smc_notify_alloc (void *pointer,
1191 size_t adress = (size_t) pointer;
1193 smc_tree_insert (adress, size);
1198 smc_notify_ignore (void *pointer)
1200 size_t adress = (size_t) pointer;
1202 smc_tree_remove (adress);
1207 smc_notify_free (void *pointer,
1210 size_t adress = (size_t) pointer;
1215 return 1; /* ignore */
1216 found_one = smc_tree_lookup (adress, &real_size);
1219 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1222 if (real_size != size && (real_size || size))
1224 fprintf (stderr, "GSlice: MemChecker: attempt to release block with invalid size: %p size=%" G_GSIZE_FORMAT " invalid-size=%" G_GSIZE_FORMAT "\n", pointer, real_size, size);
1227 if (!smc_tree_remove (adress))
1229 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1232 return 1; /* all fine */
1235 /* --- g-slice memory checker tree implementation --- */
1236 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1237 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1238 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key adress space per trunk, should distribute uniformly across BRANCH_COUNT */
1239 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1240 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1244 unsigned int n_entries;
1247 static SmcBranch **smc_tree_root = NULL;
1250 smc_tree_abort (int errval)
1252 const char *syserr = "unknown error";
1254 syserr = strerror (errval);
1256 mem_error ("MemChecker: failure in debugging tree: %s", syserr);
1259 static inline SmcEntry*
1260 smc_tree_branch_grow_L (SmcBranch *branch,
1263 unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
1264 unsigned int new_size = old_size + sizeof (branch->entries[0]);
1266 mem_assert (index <= branch->n_entries);
1267 branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
1268 if (!branch->entries)
1269 smc_tree_abort (errno);
1270 entry = branch->entries + index;
1271 g_memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
1272 branch->n_entries += 1;
1276 static inline SmcEntry*
1277 smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
1280 unsigned int n_nodes = branch->n_entries, offs = 0;
1281 SmcEntry *check = branch->entries;
1283 while (offs < n_nodes)
1285 unsigned int i = (offs + n_nodes) >> 1;
1286 check = branch->entries + i;
1287 cmp = key < check->key ? -1 : key != check->key;
1289 return check; /* return exact match */
1292 else /* (cmp > 0) */
1295 /* check points at last mismatch, cmp > 0 indicates greater key */
1296 return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
1300 smc_tree_insert (SmcKType key,
1303 unsigned int ix0, ix1;
1306 g_mutex_lock (&smc_tree_mutex);
1307 ix0 = SMC_TRUNK_HASH (key);
1308 ix1 = SMC_BRANCH_HASH (key);
1311 smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
1313 smc_tree_abort (errno);
1315 if (!smc_tree_root[ix0])
1317 smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
1318 if (!smc_tree_root[ix0])
1319 smc_tree_abort (errno);
1321 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1322 if (!entry || /* need create */
1323 entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
1324 entry->key != key) /* need insert */
1325 entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
1327 entry->value = value;
1328 g_mutex_unlock (&smc_tree_mutex);
1332 smc_tree_lookup (SmcKType key,
1335 SmcEntry *entry = NULL;
1336 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1337 gboolean found_one = FALSE;
1339 g_mutex_lock (&smc_tree_mutex);
1340 if (smc_tree_root && smc_tree_root[ix0])
1342 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1344 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1348 *value_p = entry->value;
1351 g_mutex_unlock (&smc_tree_mutex);
1356 smc_tree_remove (SmcKType key)
1358 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1359 gboolean found_one = FALSE;
1360 g_mutex_lock (&smc_tree_mutex);
1361 if (smc_tree_root && smc_tree_root[ix0])
1363 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1365 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1368 unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
1369 smc_tree_root[ix0][ix1].n_entries -= 1;
1370 g_memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
1371 if (!smc_tree_root[ix0][ix1].n_entries)
1373 /* avoid useless pressure on the memory system */
1374 free (smc_tree_root[ix0][ix1].entries);
1375 smc_tree_root[ix0][ix1].entries = NULL;
1380 g_mutex_unlock (&smc_tree_mutex);
1384 #ifdef G_ENABLE_DEBUG
1386 g_slice_debug_tree_statistics (void)
1388 g_mutex_lock (&smc_tree_mutex);
1391 unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
1393 for (i = 0; i < SMC_TRUNK_COUNT; i++)
1394 if (smc_tree_root[i])
1397 for (j = 0; j < SMC_BRANCH_COUNT; j++)
1398 if (smc_tree_root[i][j].n_entries)
1401 su += smc_tree_root[i][j].n_entries;
1402 en = MIN (en, smc_tree_root[i][j].n_entries);
1403 ex = MAX (ex, smc_tree_root[i][j].n_entries);
1405 else if (smc_tree_root[i][j].entries)
1406 o++; /* formerly used, now empty */
1409 tf = MAX (t, 1.0); /* max(1) to be a valid divisor */
1410 bf = MAX (b, 1.0); /* max(1) to be a valid divisor */
1411 fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
1412 fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1414 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
1415 fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1419 fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
1420 g_mutex_unlock (&smc_tree_mutex);
1422 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1423 * PID %CPU %MEM VSZ RSS COMMAND
1424 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1425 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1426 * 114017 103714 2354 344 0 108676 0
1427 * $ cat /proc/8887/status
1438 * (gdb) print g_slice_debug_tree_statistics ()
1439 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1440 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1441 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1444 #endif /* G_ENABLE_DEBUG */