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"
55 /* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
56 * allocator and magazine extensions as outlined in:
57 * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
58 * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
59 * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
60 * slab allocator to many cpu's and arbitrary resources.
61 * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
63 * - the thread magazines. for each (aligned) chunk size, a magazine (a list)
64 * of recently freed and soon to be allocated chunks is maintained per thread.
65 * this way, most alloc/free requests can be quickly satisfied from per-thread
66 * free lists which only require one g_private_get() call to retrive the
68 * - the magazine cache. allocating and freeing chunks to/from threads only
69 * occours at magazine sizes from a global depot of magazines. the depot
70 * maintaines a 15 second working set of allocated magazines, so full
71 * magazines are not allocated and released too often.
72 * the chunk size dependent magazine sizes automatically adapt (within limits,
73 * see [3]) to lock contention to properly scale performance across a variety
75 * - the slab allocator. this allocator allocates slabs (blocks of memory) close
76 * to the system page size or multiples thereof which have to be page aligned.
77 * the blocks are divided into smaller chunks which are used to satisfy
78 * allocations from the upper layers. the space provided by the reminder of
79 * the chunk size division is used for cache colorization (random distribution
80 * of chunk addresses) to improve processor cache utilization. multiple slabs
81 * with the same chunk size are kept in a partially sorted ring to allow O(1)
82 * freeing and allocation of chunks (as long as the allocation of an entirely
83 * new slab can be avoided).
84 * - the page allocator. on most modern systems, posix_memalign(3) or
85 * memalign(3) should be available, so this is used to allocate blocks with
86 * system page size based alignments and sizes or multiples thereof.
87 * if no memalign variant is provided, valloc() is used instead and
88 * block sizes are limited to the system page size (no multiples thereof).
89 * as a fallback, on system without even valloc(), a malloc(3)-based page
90 * allocator with alloc-only behaviour is used.
93 * [1] some systems memalign(3) implementations may rely on boundary tagging for
94 * the handed out memory chunks. to avoid excessive page-wise fragmentation,
95 * we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
96 * specified in NATIVE_MALLOC_PADDING.
97 * [2] using the slab allocator alone already provides for a fast and efficient
98 * allocator, it doesn't properly scale beyond single-threaded uses though.
99 * also, the slab allocator implements eager free(3)-ing, i.e. does not
100 * provide any form of caching or working set maintenance. so if used alone,
101 * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
102 * at certain thresholds.
103 * [3] magazine sizes are bound by an implementation specific minimum size and
104 * a chunk size specific maximum to limit magazine storage sizes to roughly
106 * [4] allocating ca. 8 chunks per block/page keeps a good balance between
107 * external and internal fragmentation (<= 12.5%). [Bonwick94]
110 /* --- macros and constants --- */
111 #define LARGEALIGNMENT (256)
112 #define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
113 #define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
114 #define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
115 #define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
116 #define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
117 #define MIN_MAGAZINE_SIZE (4)
118 #define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
119 #define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
120 #define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
121 #define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
122 #define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
123 #define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
125 /* optimized version of ALIGN (size, P2ALIGNMENT) */
126 #if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
127 #define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
128 #elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
129 #define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
131 #define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
134 /* special helpers to avoid gmessage.c dependency */
135 static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
136 #define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
138 /* --- structures --- */
139 typedef struct _ChunkLink ChunkLink;
140 typedef struct _SlabInfo SlabInfo;
141 typedef struct _CachedMagazine CachedMagazine;
149 SlabInfo *next, *prev;
153 gsize count; /* approximative chunks list length */
156 Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */
157 Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */
160 gboolean always_malloc;
161 gboolean bypass_magazines;
162 gboolean debug_blocks;
163 gsize working_set_msecs;
164 guint color_increment;
167 /* const after initialization */
168 gsize min_page_size, max_page_size;
170 gsize max_slab_chunk_size_for_magazine_cache;
172 GMutex magazine_mutex;
173 ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */
174 guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */
180 SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */
184 /* --- g-slice prototypes --- */
185 static gpointer slab_allocator_alloc_chunk (gsize chunk_size);
186 static void slab_allocator_free_chunk (gsize chunk_size,
188 static void private_thread_memory_cleanup (gpointer data);
189 static gpointer allocator_memalign (gsize alignment,
191 static void allocator_memfree (gsize memsize,
193 static inline void magazine_cache_update_stamp (void);
194 static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
197 /* --- g-slice memory checker --- */
198 static void smc_notify_alloc (void *pointer,
200 static int smc_notify_free (void *pointer,
203 /* --- variables --- */
204 static GPrivate private_thread_memory = G_PRIVATE_INIT (private_thread_memory_cleanup);
205 static gsize sys_page_size = 0;
206 static Allocator allocator[1] = { { 0, }, };
207 static SliceConfig slice_config = {
208 FALSE, /* always_malloc */
209 FALSE, /* bypass_magazines */
210 FALSE, /* debug_blocks */
211 15 * 1000, /* working_set_msecs */
212 1, /* color increment, alt: 0x7fffffff */
214 static GMutex smc_tree_mutex; /* mutex for G_SLICE=debug-blocks */
216 /* --- auxiliary funcitons --- */
218 g_slice_set_config (GSliceConfig ckey,
221 g_return_if_fail (sys_page_size == 0);
224 case G_SLICE_CONFIG_ALWAYS_MALLOC:
225 slice_config.always_malloc = value != 0;
227 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
228 slice_config.bypass_magazines = value != 0;
230 case G_SLICE_CONFIG_WORKING_SET_MSECS:
231 slice_config.working_set_msecs = value;
233 case G_SLICE_CONFIG_COLOR_INCREMENT:
234 slice_config.color_increment = value;
240 g_slice_get_config (GSliceConfig ckey)
244 case G_SLICE_CONFIG_ALWAYS_MALLOC:
245 return slice_config.always_malloc;
246 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
247 return slice_config.bypass_magazines;
248 case G_SLICE_CONFIG_WORKING_SET_MSECS:
249 return slice_config.working_set_msecs;
250 case G_SLICE_CONFIG_CHUNK_SIZES:
251 return MAX_SLAB_INDEX (allocator);
252 case G_SLICE_CONFIG_COLOR_INCREMENT:
253 return slice_config.color_increment;
260 g_slice_get_config_state (GSliceConfig ckey,
265 g_return_val_if_fail (n_values != NULL, NULL);
270 case G_SLICE_CONFIG_CONTENTION_COUNTER:
271 array[i++] = SLAB_CHUNK_SIZE (allocator, address);
272 array[i++] = allocator->contention_counters[address];
273 array[i++] = allocator_get_magazine_threshold (allocator, address);
275 return g_memdup (array, sizeof (array[0]) * *n_values);
282 slice_config_init (SliceConfig *config)
284 /* don't use g_malloc/g_message here */
286 const gchar *val = _g_getenv_nomalloc ("G_SLICE", buffer);
287 const GDebugKey keys[] = {
288 { "always-malloc", 1 << 0 },
289 { "debug-blocks", 1 << 1 },
291 gint flags = !val ? 0 : g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
292 *config = slice_config;
293 if (flags & (1 << 0)) /* always-malloc */
294 config->always_malloc = TRUE;
295 if (flags & (1 << 1)) /* debug-blocks */
296 config->debug_blocks = TRUE;
300 g_slice_init_nomessage (void)
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 */
362 allocator_categorize (gsize aligned_chunk_size)
364 /* speed up the likely path */
365 if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
366 return 1; /* use magazine cache */
368 if (!allocator->config.always_malloc &&
369 aligned_chunk_size &&
370 aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
372 if (allocator->config.bypass_magazines)
373 return 2; /* use slab allocator, see [2] */
374 return 1; /* use magazine cache */
376 return 0; /* use malloc() */
380 g_mutex_lock_a (GMutex *mutex,
381 guint *contention_counter)
383 gboolean contention = FALSE;
384 if (!g_mutex_trylock (mutex))
386 g_mutex_lock (mutex);
391 allocator->mutex_counter++;
392 if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
394 allocator->mutex_counter = 0;
395 *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
398 else /* !contention */
400 allocator->mutex_counter--;
401 if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
403 allocator->mutex_counter = 0;
404 *contention_counter = MAX (*contention_counter, 1) - 1;
409 static inline ThreadMemory*
410 thread_memory_from_self (void)
412 ThreadMemory *tmem = g_private_get (&private_thread_memory);
413 if (G_UNLIKELY (!tmem))
415 static GMutex init_mutex;
418 g_mutex_lock (&init_mutex);
419 if G_UNLIKELY (sys_page_size == 0)
420 g_slice_init_nomessage ();
421 g_mutex_unlock (&init_mutex);
423 n_magazines = MAX_SLAB_INDEX (allocator);
424 tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
425 tmem->magazine1 = (Magazine*) (tmem + 1);
426 tmem->magazine2 = &tmem->magazine1[n_magazines];
427 g_private_set (&private_thread_memory, tmem);
432 static inline ChunkLink*
433 magazine_chain_pop_head (ChunkLink **magazine_chunks)
435 /* magazine chains are linked via ChunkLink->next.
436 * each ChunkLink->data of the toplevel chain may point to a subchain,
437 * linked via ChunkLink->next. ChunkLink->data of the subchains just
438 * contains uninitialized junk.
440 ChunkLink *chunk = (*magazine_chunks)->data;
441 if (G_UNLIKELY (chunk))
443 /* allocating from freed list */
444 (*magazine_chunks)->data = chunk->next;
448 chunk = *magazine_chunks;
449 *magazine_chunks = chunk->next;
454 #if 0 /* useful for debugging */
456 magazine_count (ChunkLink *head)
463 ChunkLink *child = head->data;
465 for (child = head->data; child; child = child->next)
474 allocator_get_magazine_threshold (Allocator *allocator,
477 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
478 * which is required by the implementation. also, for moderately sized chunks
479 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
480 * of chunks available per page/2 to avoid excessive traffic in the magazine
481 * cache for small to medium sized structures.
482 * the upper bound of the magazine size is effectively provided by
483 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
484 * the content of a single magazine doesn't exceed ca. 16KB.
486 gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
487 guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
488 guint contention_counter = allocator->contention_counters[ix];
489 if (G_UNLIKELY (contention_counter)) /* single CPU bias */
491 /* adapt contention counter thresholds to chunk sizes */
492 contention_counter = contention_counter * 64 / chunk_size;
493 threshold = MAX (threshold, contention_counter);
498 /* --- magazine cache --- */
500 magazine_cache_update_stamp (void)
502 if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
505 g_get_current_time (&tv);
506 allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000; /* milli seconds */
507 allocator->stamp_counter = 0;
510 allocator->stamp_counter++;
513 static inline ChunkLink*
514 magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
520 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
521 /* ensure a magazine with at least 4 unused data pointers */
522 chunk1 = magazine_chain_pop_head (&magazine_chunks);
523 chunk2 = magazine_chain_pop_head (&magazine_chunks);
524 chunk3 = magazine_chain_pop_head (&magazine_chunks);
525 chunk4 = magazine_chain_pop_head (&magazine_chunks);
526 chunk4->next = magazine_chunks;
527 chunk3->next = chunk4;
528 chunk2->next = chunk3;
529 chunk1->next = chunk2;
533 /* access the first 3 fields of a specially prepared magazine chain */
534 #define magazine_chain_prev(mc) ((mc)->data)
535 #define magazine_chain_stamp(mc) ((mc)->next->data)
536 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
537 #define magazine_chain_next(mc) ((mc)->next->next->data)
538 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
541 magazine_cache_trim (Allocator *allocator,
545 /* g_mutex_lock (allocator->mutex); done by caller */
546 /* trim magazine cache from tail */
547 ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
548 ChunkLink *trash = NULL;
549 while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator->config.working_set_msecs)
552 ChunkLink *prev = magazine_chain_prev (current);
553 ChunkLink *next = magazine_chain_next (current);
554 magazine_chain_next (prev) = next;
555 magazine_chain_prev (next) = prev;
556 /* clear special fields, put on trash stack */
557 magazine_chain_next (current) = NULL;
558 magazine_chain_count (current) = NULL;
559 magazine_chain_stamp (current) = NULL;
560 magazine_chain_prev (current) = trash;
562 /* fixup list head if required */
563 if (current == allocator->magazines[ix])
565 allocator->magazines[ix] = NULL;
570 g_mutex_unlock (&allocator->magazine_mutex);
574 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
575 g_mutex_lock (&allocator->slab_mutex);
579 trash = magazine_chain_prev (current);
580 magazine_chain_prev (current) = NULL; /* clear special field */
583 ChunkLink *chunk = magazine_chain_pop_head (¤t);
584 slab_allocator_free_chunk (chunk_size, chunk);
587 g_mutex_unlock (&allocator->slab_mutex);
592 magazine_cache_push_magazine (guint ix,
593 ChunkLink *magazine_chunks,
594 gsize count) /* must be >= MIN_MAGAZINE_SIZE */
596 ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
597 ChunkLink *next, *prev;
598 g_mutex_lock (&allocator->magazine_mutex);
599 /* add magazine at head */
600 next = allocator->magazines[ix];
602 prev = magazine_chain_prev (next);
604 next = prev = current;
605 magazine_chain_next (prev) = current;
606 magazine_chain_prev (next) = current;
607 magazine_chain_prev (current) = prev;
608 magazine_chain_next (current) = next;
609 magazine_chain_count (current) = (gpointer) count;
611 magazine_cache_update_stamp();
612 magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
613 allocator->magazines[ix] = current;
614 /* free old magazines beyond a certain threshold */
615 magazine_cache_trim (allocator, ix, allocator->last_stamp);
616 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
620 magazine_cache_pop_magazine (guint ix,
623 g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]);
624 if (!allocator->magazines[ix])
626 guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
627 gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
628 ChunkLink *chunk, *head;
629 g_mutex_unlock (&allocator->magazine_mutex);
630 g_mutex_lock (&allocator->slab_mutex);
631 head = slab_allocator_alloc_chunk (chunk_size);
634 for (i = 1; i < magazine_threshold; i++)
636 chunk->next = slab_allocator_alloc_chunk (chunk_size);
641 g_mutex_unlock (&allocator->slab_mutex);
647 ChunkLink *current = allocator->magazines[ix];
648 ChunkLink *prev = magazine_chain_prev (current);
649 ChunkLink *next = magazine_chain_next (current);
651 magazine_chain_next (prev) = next;
652 magazine_chain_prev (next) = prev;
653 allocator->magazines[ix] = next == current ? NULL : next;
654 g_mutex_unlock (&allocator->magazine_mutex);
655 /* clear special fields and hand out */
656 *countp = (gsize) magazine_chain_count (current);
657 magazine_chain_prev (current) = NULL;
658 magazine_chain_next (current) = NULL;
659 magazine_chain_count (current) = NULL;
660 magazine_chain_stamp (current) = NULL;
665 /* --- thread magazines --- */
667 private_thread_memory_cleanup (gpointer data)
669 ThreadMemory *tmem = data;
670 const guint n_magazines = MAX_SLAB_INDEX (allocator);
672 for (ix = 0; ix < n_magazines; ix++)
676 mags[0] = &tmem->magazine1[ix];
677 mags[1] = &tmem->magazine2[ix];
678 for (j = 0; j < 2; j++)
680 Magazine *mag = mags[j];
681 if (mag->count >= MIN_MAGAZINE_SIZE)
682 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
685 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
686 g_mutex_lock (&allocator->slab_mutex);
689 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
690 slab_allocator_free_chunk (chunk_size, chunk);
692 g_mutex_unlock (&allocator->slab_mutex);
700 thread_memory_magazine1_reload (ThreadMemory *tmem,
703 Magazine *mag = &tmem->magazine1[ix];
704 mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
706 mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
710 thread_memory_magazine2_unload (ThreadMemory *tmem,
713 Magazine *mag = &tmem->magazine2[ix];
714 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
720 thread_memory_swap_magazines (ThreadMemory *tmem,
723 Magazine xmag = tmem->magazine1[ix];
724 tmem->magazine1[ix] = tmem->magazine2[ix];
725 tmem->magazine2[ix] = xmag;
728 static inline gboolean
729 thread_memory_magazine1_is_empty (ThreadMemory *tmem,
732 return tmem->magazine1[ix].chunks == NULL;
735 static inline gboolean
736 thread_memory_magazine2_is_full (ThreadMemory *tmem,
739 return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
742 static inline gpointer
743 thread_memory_magazine1_alloc (ThreadMemory *tmem,
746 Magazine *mag = &tmem->magazine1[ix];
747 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
748 if (G_LIKELY (mag->count > 0))
754 thread_memory_magazine2_free (ThreadMemory *tmem,
758 Magazine *mag = &tmem->magazine2[ix];
759 ChunkLink *chunk = mem;
761 chunk->next = mag->chunks;
766 /* --- API functions --- */
768 g_slice_alloc (gsize mem_size)
775 /* This gets the private structure for this thread. If the private
776 * structure does not yet exist, it is created.
778 * This has a side effect of causing GSlice to be initialised, so it
781 tmem = thread_memory_from_self ();
783 chunk_size = P2ALIGN (mem_size);
784 acat = allocator_categorize (chunk_size);
785 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
787 guint ix = SLAB_INDEX (allocator, chunk_size);
788 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
790 thread_memory_swap_magazines (tmem, ix);
791 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
792 thread_memory_magazine1_reload (tmem, ix);
794 mem = thread_memory_magazine1_alloc (tmem, ix);
796 else if (acat == 2) /* allocate through slab allocator */
798 g_mutex_lock (&allocator->slab_mutex);
799 mem = slab_allocator_alloc_chunk (chunk_size);
800 g_mutex_unlock (&allocator->slab_mutex);
802 else /* delegate to system malloc */
803 mem = g_malloc (mem_size);
804 if (G_UNLIKELY (allocator->config.debug_blocks))
805 smc_notify_alloc (mem, mem_size);
807 TRACE (GLIB_SLICE_ALLOC((void*)mem, mem_size));
813 g_slice_alloc0 (gsize mem_size)
815 gpointer mem = g_slice_alloc (mem_size);
817 memset (mem, 0, mem_size);
822 g_slice_copy (gsize mem_size,
823 gconstpointer mem_block)
825 gpointer mem = g_slice_alloc (mem_size);
827 memcpy (mem, mem_block, mem_size);
832 g_slice_free1 (gsize mem_size,
835 gsize chunk_size = P2ALIGN (mem_size);
836 guint acat = allocator_categorize (chunk_size);
837 if (G_UNLIKELY (!mem_block))
839 if (G_UNLIKELY (allocator->config.debug_blocks) &&
840 !smc_notify_free (mem_block, mem_size))
842 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
844 ThreadMemory *tmem = thread_memory_from_self();
845 guint ix = SLAB_INDEX (allocator, chunk_size);
846 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
848 thread_memory_swap_magazines (tmem, ix);
849 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
850 thread_memory_magazine2_unload (tmem, ix);
852 if (G_UNLIKELY (g_mem_gc_friendly))
853 memset (mem_block, 0, chunk_size);
854 thread_memory_magazine2_free (tmem, ix, mem_block);
856 else if (acat == 2) /* allocate through slab allocator */
858 if (G_UNLIKELY (g_mem_gc_friendly))
859 memset (mem_block, 0, chunk_size);
860 g_mutex_lock (&allocator->slab_mutex);
861 slab_allocator_free_chunk (chunk_size, mem_block);
862 g_mutex_unlock (&allocator->slab_mutex);
864 else /* delegate to system malloc */
866 if (G_UNLIKELY (g_mem_gc_friendly))
867 memset (mem_block, 0, mem_size);
870 TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size));
874 g_slice_free_chain_with_offset (gsize mem_size,
878 gpointer slice = mem_chain;
879 /* while the thread magazines and the magazine cache are implemented so that
880 * they can easily be extended to allow for free lists containing more free
881 * lists for the first level nodes, which would allow O(1) freeing in this
882 * function, the benefit of such an extension is questionable, because:
883 * - the magazine size counts will become mere lower bounds which confuses
884 * the code adapting to lock contention;
885 * - freeing a single node to the thread magazines is very fast, so this
886 * O(list_length) operation is multiplied by a fairly small factor;
887 * - memory usage histograms on larger applications seem to indicate that
888 * the amount of released multi node lists is negligible in comparison
889 * to single node releases.
890 * - the major performance bottle neck, namely g_private_get() or
891 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
892 * inner loop for freeing chained slices.
894 gsize chunk_size = P2ALIGN (mem_size);
895 guint acat = allocator_categorize (chunk_size);
896 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
898 ThreadMemory *tmem = thread_memory_from_self();
899 guint ix = SLAB_INDEX (allocator, chunk_size);
902 guint8 *current = slice;
903 slice = *(gpointer*) (current + next_offset);
904 if (G_UNLIKELY (allocator->config.debug_blocks) &&
905 !smc_notify_free (current, mem_size))
907 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
909 thread_memory_swap_magazines (tmem, ix);
910 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
911 thread_memory_magazine2_unload (tmem, ix);
913 if (G_UNLIKELY (g_mem_gc_friendly))
914 memset (current, 0, chunk_size);
915 thread_memory_magazine2_free (tmem, ix, current);
918 else if (acat == 2) /* allocate through slab allocator */
920 g_mutex_lock (&allocator->slab_mutex);
923 guint8 *current = slice;
924 slice = *(gpointer*) (current + next_offset);
925 if (G_UNLIKELY (allocator->config.debug_blocks) &&
926 !smc_notify_free (current, mem_size))
928 if (G_UNLIKELY (g_mem_gc_friendly))
929 memset (current, 0, chunk_size);
930 slab_allocator_free_chunk (chunk_size, current);
932 g_mutex_unlock (&allocator->slab_mutex);
934 else /* delegate to system malloc */
937 guint8 *current = slice;
938 slice = *(gpointer*) (current + next_offset);
939 if (G_UNLIKELY (allocator->config.debug_blocks) &&
940 !smc_notify_free (current, mem_size))
942 if (G_UNLIKELY (g_mem_gc_friendly))
943 memset (current, 0, mem_size);
948 /* --- single page allocator --- */
950 allocator_slab_stack_push (Allocator *allocator,
954 /* insert slab at slab ring head */
955 if (!allocator->slab_stack[ix])
962 SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
968 allocator->slab_stack[ix] = sinfo;
972 allocator_aligned_page_size (Allocator *allocator,
975 gsize val = 1 << g_bit_storage (n_bytes - 1);
976 val = MAX (val, allocator->min_page_size);
981 allocator_add_slab (Allocator *allocator,
987 gsize addr, padding, n_chunks, color = 0;
988 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
989 /* allocate 1 page for the chunks and the slab */
990 gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
991 guint8 *mem = aligned_memory;
995 const gchar *syserr = "unknown error";
997 syserr = strerror (errno);
999 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
1000 (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
1002 /* mask page address */
1003 addr = ((gsize) mem / page_size) * page_size;
1004 /* assert alignment */
1005 mem_assert (aligned_memory == (gpointer) addr);
1006 /* basic slab info setup */
1007 sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
1008 sinfo->n_allocated = 0;
1009 sinfo->chunks = NULL;
1010 /* figure cache colorization */
1011 n_chunks = ((guint8*) sinfo - mem) / chunk_size;
1012 padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
1015 color = (allocator->color_accu * P2ALIGNMENT) % padding;
1016 allocator->color_accu += allocator->config.color_increment;
1018 /* add chunks to free list */
1019 chunk = (ChunkLink*) (mem + color);
1020 sinfo->chunks = chunk;
1021 for (i = 0; i < n_chunks - 1; i++)
1023 chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
1024 chunk = chunk->next;
1026 chunk->next = NULL; /* last chunk */
1027 /* add slab to slab ring */
1028 allocator_slab_stack_push (allocator, ix, sinfo);
1032 slab_allocator_alloc_chunk (gsize chunk_size)
1035 guint ix = SLAB_INDEX (allocator, chunk_size);
1036 /* ensure non-empty slab */
1037 if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
1038 allocator_add_slab (allocator, ix, chunk_size);
1039 /* allocate chunk */
1040 chunk = allocator->slab_stack[ix]->chunks;
1041 allocator->slab_stack[ix]->chunks = chunk->next;
1042 allocator->slab_stack[ix]->n_allocated++;
1043 /* rotate empty slabs */
1044 if (!allocator->slab_stack[ix]->chunks)
1045 allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
1050 slab_allocator_free_chunk (gsize chunk_size,
1055 guint ix = SLAB_INDEX (allocator, chunk_size);
1056 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1057 gsize addr = ((gsize) mem / page_size) * page_size;
1058 /* mask page address */
1059 guint8 *page = (guint8*) addr;
1060 SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
1061 /* assert valid chunk count */
1062 mem_assert (sinfo->n_allocated > 0);
1063 /* add chunk to free list */
1064 was_empty = sinfo->chunks == NULL;
1065 chunk = (ChunkLink*) mem;
1066 chunk->next = sinfo->chunks;
1067 sinfo->chunks = chunk;
1068 sinfo->n_allocated--;
1069 /* keep slab ring partially sorted, empty slabs at end */
1073 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1076 if (allocator->slab_stack[ix] == sinfo)
1077 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1078 /* insert slab at head */
1079 allocator_slab_stack_push (allocator, ix, sinfo);
1081 /* eagerly free complete unused slabs */
1082 if (!sinfo->n_allocated)
1085 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1088 if (allocator->slab_stack[ix] == sinfo)
1089 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1091 allocator_memfree (page_size, page);
1095 /* --- memalign implementation --- */
1096 #ifdef HAVE_MALLOC_H
1097 #include <malloc.h> /* memalign() */
1101 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1102 * define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
1103 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1104 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1105 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1108 #if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1109 static GTrashStack *compat_valloc_trash = NULL;
1113 allocator_memalign (gsize alignment,
1116 gpointer aligned_memory = NULL;
1118 #if HAVE_COMPLIANT_POSIX_MEMALIGN
1119 err = posix_memalign (&aligned_memory, alignment, memsize);
1122 aligned_memory = memalign (alignment, memsize);
1126 aligned_memory = valloc (memsize);
1129 /* simplistic non-freeing page allocator */
1130 mem_assert (alignment == sys_page_size);
1131 mem_assert (memsize <= sys_page_size);
1132 if (!compat_valloc_trash)
1134 const guint n_pages = 16;
1135 guint8 *mem = malloc (n_pages * sys_page_size);
1140 guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
1142 i--; /* mem wasn't page aligned */
1144 g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
1147 aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
1149 if (!aligned_memory)
1151 return aligned_memory;
1155 allocator_memfree (gsize memsize,
1158 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1161 mem_assert (memsize <= sys_page_size);
1162 g_trash_stack_push (&compat_valloc_trash, mem);
1167 mem_error (const char *format,
1172 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1173 fputs ("\n***MEMORY-ERROR***: ", stderr);
1174 pname = g_get_prgname();
1175 fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid());
1176 va_start (args, format);
1177 vfprintf (stderr, format, args);
1179 fputs ("\n", stderr);
1184 /* --- g-slice memory checker tree --- */
1185 typedef size_t SmcKType; /* key type */
1186 typedef size_t SmcVType; /* value type */
1191 static void smc_tree_insert (SmcKType key,
1193 static gboolean smc_tree_lookup (SmcKType key,
1195 static gboolean smc_tree_remove (SmcKType key);
1198 /* --- g-slice memory checker implementation --- */
1200 smc_notify_alloc (void *pointer,
1203 size_t adress = (size_t) pointer;
1205 smc_tree_insert (adress, size);
1210 smc_notify_ignore (void *pointer)
1212 size_t adress = (size_t) pointer;
1214 smc_tree_remove (adress);
1219 smc_notify_free (void *pointer,
1222 size_t adress = (size_t) pointer;
1227 return 1; /* ignore */
1228 found_one = smc_tree_lookup (adress, &real_size);
1231 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1234 if (real_size != size && (real_size || size))
1236 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);
1239 if (!smc_tree_remove (adress))
1241 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1244 return 1; /* all fine */
1247 /* --- g-slice memory checker tree implementation --- */
1248 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1249 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1250 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key adress space per trunk, should distribute uniformly across BRANCH_COUNT */
1251 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1252 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1256 unsigned int n_entries;
1259 static SmcBranch **smc_tree_root = NULL;
1262 smc_tree_abort (int errval)
1264 const char *syserr = "unknown error";
1266 syserr = strerror (errval);
1268 mem_error ("MemChecker: failure in debugging tree: %s", syserr);
1271 static inline SmcEntry*
1272 smc_tree_branch_grow_L (SmcBranch *branch,
1275 unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
1276 unsigned int new_size = old_size + sizeof (branch->entries[0]);
1278 mem_assert (index <= branch->n_entries);
1279 branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
1280 if (!branch->entries)
1281 smc_tree_abort (errno);
1282 entry = branch->entries + index;
1283 g_memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
1284 branch->n_entries += 1;
1288 static inline SmcEntry*
1289 smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
1292 unsigned int n_nodes = branch->n_entries, offs = 0;
1293 SmcEntry *check = branch->entries;
1295 while (offs < n_nodes)
1297 unsigned int i = (offs + n_nodes) >> 1;
1298 check = branch->entries + i;
1299 cmp = key < check->key ? -1 : key != check->key;
1301 return check; /* return exact match */
1304 else /* (cmp > 0) */
1307 /* check points at last mismatch, cmp > 0 indicates greater key */
1308 return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
1312 smc_tree_insert (SmcKType key,
1315 unsigned int ix0, ix1;
1318 g_mutex_lock (&smc_tree_mutex);
1319 ix0 = SMC_TRUNK_HASH (key);
1320 ix1 = SMC_BRANCH_HASH (key);
1323 smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
1325 smc_tree_abort (errno);
1327 if (!smc_tree_root[ix0])
1329 smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
1330 if (!smc_tree_root[ix0])
1331 smc_tree_abort (errno);
1333 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1334 if (!entry || /* need create */
1335 entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
1336 entry->key != key) /* need insert */
1337 entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
1339 entry->value = value;
1340 g_mutex_unlock (&smc_tree_mutex);
1344 smc_tree_lookup (SmcKType key,
1347 SmcEntry *entry = NULL;
1348 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1349 gboolean found_one = FALSE;
1351 g_mutex_lock (&smc_tree_mutex);
1352 if (smc_tree_root && smc_tree_root[ix0])
1354 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1356 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1360 *value_p = entry->value;
1363 g_mutex_unlock (&smc_tree_mutex);
1368 smc_tree_remove (SmcKType key)
1370 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1371 gboolean found_one = FALSE;
1372 g_mutex_lock (&smc_tree_mutex);
1373 if (smc_tree_root && smc_tree_root[ix0])
1375 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1377 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1380 unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
1381 smc_tree_root[ix0][ix1].n_entries -= 1;
1382 g_memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
1383 if (!smc_tree_root[ix0][ix1].n_entries)
1385 /* avoid useless pressure on the memory system */
1386 free (smc_tree_root[ix0][ix1].entries);
1387 smc_tree_root[ix0][ix1].entries = NULL;
1392 g_mutex_unlock (&smc_tree_mutex);
1396 #ifdef G_ENABLE_DEBUG
1398 g_slice_debug_tree_statistics (void)
1400 g_mutex_lock (&smc_tree_mutex);
1403 unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
1405 for (i = 0; i < SMC_TRUNK_COUNT; i++)
1406 if (smc_tree_root[i])
1409 for (j = 0; j < SMC_BRANCH_COUNT; j++)
1410 if (smc_tree_root[i][j].n_entries)
1413 su += smc_tree_root[i][j].n_entries;
1414 en = MIN (en, smc_tree_root[i][j].n_entries);
1415 ex = MAX (ex, smc_tree_root[i][j].n_entries);
1417 else if (smc_tree_root[i][j].entries)
1418 o++; /* formerly used, now empty */
1421 tf = MAX (t, 1.0); /* max(1) to be a valid divisor */
1422 bf = MAX (b, 1.0); /* max(1) to be a valid divisor */
1423 fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
1424 fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1426 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
1427 fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1431 fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
1432 g_mutex_unlock (&smc_tree_mutex);
1434 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1435 * PID %CPU %MEM VSZ RSS COMMAND
1436 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1437 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1438 * 114017 103714 2354 344 0 108676 0
1439 * $ cat /proc/8887/status
1450 * (gdb) print g_slice_debug_tree_statistics ()
1451 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1452 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1453 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1456 #endif /* G_ENABLE_DEBUG */