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.
23 #if defined HAVE_POSIX_MEMALIGN && defined POSIX_MEMALIGN_WITH_COMPLIANT_ALLOCS
24 # define HAVE_COMPLIANT_POSIX_MEMALIGN 1
27 #ifdef HAVE_COMPLIANT_POSIX_MEMALIGN
28 #define _XOPEN_SOURCE 600 /* posix_memalign() */
30 #include <stdlib.h> /* posix_memalign() */
33 #include "gmem.h" /* gslice.h */
34 #include "gthreadprivate.h"
38 #include <unistd.h> /* sysconf() */
45 #include <stdio.h> /* fputs/fprintf */
48 /* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
49 * allocator and magazine extensions as outlined in:
50 * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
51 * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
52 * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
53 * slab allocator to many cpu's and arbitrary resources.
54 * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
56 * - the thread magazines. for each (aligned) chunk size, a magazine (a list)
57 * of recently freed and soon to be allocated chunks is maintained per thread.
58 * this way, most alloc/free requests can be quickly satisfied from per-thread
59 * free lists which only require one g_private_get() call to retrive the
61 * - the magazine cache. allocating and freeing chunks to/from threads only
62 * occours at magazine sizes from a global depot of magazines. the depot
63 * maintaines a 15 second working set of allocated magazines, so full
64 * magazines are not allocated and released too often.
65 * the chunk size dependent magazine sizes automatically adapt (within limits,
66 * see [3]) to lock contention to properly scale performance across a variety
68 * - the slab allocator. this allocator allocates slabs (blocks of memory) close
69 * to the system page size or multiples thereof which have to be page aligned.
70 * the blocks are divided into smaller chunks which are used to satisfy
71 * allocations from the upper layers. the space provided by the reminder of
72 * the chunk size division is used for cache colorization (random distribution
73 * of chunk addresses) to improve processor cache utilization. multiple slabs
74 * with the same chunk size are kept in a partially sorted ring to allow O(1)
75 * freeing and allocation of chunks (as long as the allocation of an entirely
76 * new slab can be avoided).
77 * - the page allocator. on most modern systems, posix_memalign(3) or
78 * memalign(3) should be available, so this is used to allocate blocks with
79 * system page size based alignments and sizes or multiples thereof.
80 * if no memalign variant is provided, valloc() is used instead and
81 * block sizes are limited to the system page size (no multiples thereof).
82 * as a fallback, on system without even valloc(), a malloc(3)-based page
83 * allocator with alloc-only behaviour is used.
86 * [1] some systems memalign(3) implementations may rely on boundary tagging for
87 * the handed out memory chunks. to avoid excessive page-wise fragmentation,
88 * we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
89 * specified in NATIVE_MALLOC_PADDING.
90 * [2] using the slab allocator alone already provides for a fast and efficient
91 * allocator, it doesn't properly scale beyond single-threaded uses though.
92 * also, the slab allocator implements eager free(3)-ing, i.e. does not
93 * provide any form of caching or working set maintenance. so if used alone,
94 * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
95 * at certain thresholds.
96 * [3] magazine sizes are bound by an implementation specific minimum size and
97 * a chunk size specific maximum to limit magazine storage sizes to roughly
99 * [4] allocating ca. 8 chunks per block/page keeps a good balance between
100 * external and internal fragmentation (<= 12.5%). [Bonwick94]
103 /* --- macros and constants --- */
104 #define LARGEALIGNMENT (256)
105 #define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
106 #define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
107 #define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
108 #define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
109 #define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
110 #define MIN_MAGAZINE_SIZE (4)
111 #define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
112 #define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
113 #define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
114 #define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
115 #define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
116 #define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
118 /* optimized version of ALIGN (size, P2ALIGNMENT) */
119 #if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
120 #define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
121 #elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
122 #define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
124 #define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
127 /* special helpers to avoid gmessage.c dependency */
128 static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
129 #define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
131 /* --- structures --- */
132 typedef struct _ChunkLink ChunkLink;
133 typedef struct _SlabInfo SlabInfo;
134 typedef struct _CachedMagazine CachedMagazine;
142 SlabInfo *next, *prev;
146 gsize count; /* approximative chunks list length */
149 Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */
150 Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */
153 gboolean always_malloc;
154 gboolean bypass_magazines;
155 gboolean debug_blocks;
156 gsize working_set_msecs;
157 guint color_increment;
160 /* const after initialization */
161 gsize min_page_size, max_page_size;
163 gsize max_slab_chunk_size_for_magazine_cache;
165 GMutex *magazine_mutex;
166 ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */
167 guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */
173 SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */
177 /* --- g-slice prototypes --- */
178 static gpointer slab_allocator_alloc_chunk (gsize chunk_size);
179 static void slab_allocator_free_chunk (gsize chunk_size,
181 static void private_thread_memory_cleanup (gpointer data);
182 static gpointer allocator_memalign (gsize alignment,
184 static void allocator_memfree (gsize memsize,
186 static inline void magazine_cache_update_stamp (void);
187 static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
190 /* --- g-slice memory checker --- */
191 static void smc_notify_alloc (void *pointer,
193 static int smc_notify_free (void *pointer,
196 /* --- variables --- */
197 static GPrivate *private_thread_memory = NULL;
198 static gsize sys_page_size = 0;
199 static Allocator allocator[1] = { { 0, }, };
200 static SliceConfig slice_config = {
201 FALSE, /* always_malloc */
202 FALSE, /* bypass_magazines */
203 FALSE, /* debug_blocks */
204 15 * 1000, /* working_set_msecs */
205 1, /* color increment, alt: 0x7fffffff */
207 static GMutex *smc_tree_mutex = NULL; /* mutex for G_SLICE=debug-blocks */
209 /* --- auxillary funcitons --- */
211 g_slice_set_config (GSliceConfig ckey,
214 g_return_if_fail (sys_page_size == 0);
217 case G_SLICE_CONFIG_ALWAYS_MALLOC:
218 slice_config.always_malloc = value != 0;
220 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
221 slice_config.bypass_magazines = value != 0;
223 case G_SLICE_CONFIG_WORKING_SET_MSECS:
224 slice_config.working_set_msecs = value;
226 case G_SLICE_CONFIG_COLOR_INCREMENT:
227 slice_config.color_increment = value;
233 g_slice_get_config (GSliceConfig ckey)
237 case G_SLICE_CONFIG_ALWAYS_MALLOC:
238 return slice_config.always_malloc;
239 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
240 return slice_config.bypass_magazines;
241 case G_SLICE_CONFIG_WORKING_SET_MSECS:
242 return slice_config.working_set_msecs;
243 case G_SLICE_CONFIG_CHUNK_SIZES:
244 return MAX_SLAB_INDEX (allocator);
245 case G_SLICE_CONFIG_COLOR_INCREMENT:
246 return slice_config.color_increment;
253 g_slice_get_config_state (GSliceConfig ckey,
258 g_return_val_if_fail (n_values != NULL, NULL);
263 case G_SLICE_CONFIG_CONTENTION_COUNTER:
264 array[i++] = SLAB_CHUNK_SIZE (allocator, address);
265 array[i++] = allocator->contention_counters[address];
266 array[i++] = allocator_get_magazine_threshold (allocator, address);
268 return g_memdup (array, sizeof (array[0]) * *n_values);
275 slice_config_init (SliceConfig *config)
277 /* don't use g_malloc/g_message here */
279 const gchar *val = _g_getenv_nomalloc ("G_SLICE", buffer);
280 static const GDebugKey keys[] = {
281 { "always-malloc", 1 << 0 },
282 { "debug-blocks", 1 << 1 },
284 gint flags = !val ? 0 : g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
285 *config = slice_config;
286 if (flags & (1 << 0)) /* always-malloc */
287 config->always_malloc = TRUE;
288 if (flags & (1 << 1)) /* debug-blocks */
289 config->debug_blocks = TRUE;
293 g_slice_init_nomessage (void)
295 /* we may not use g_error() or friends here */
296 mem_assert (sys_page_size == 0);
297 mem_assert (MIN_MAGAZINE_SIZE >= 4);
301 SYSTEM_INFO system_info;
302 GetSystemInfo (&system_info);
303 sys_page_size = system_info.dwPageSize;
306 sys_page_size = sysconf (_SC_PAGESIZE); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */
308 mem_assert (sys_page_size >= 2 * LARGEALIGNMENT);
309 mem_assert ((sys_page_size & (sys_page_size - 1)) == 0);
310 slice_config_init (&allocator->config);
311 allocator->min_page_size = sys_page_size;
312 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN
313 /* allow allocation of pages up to 8KB (with 8KB alignment).
314 * this is useful because many medium to large sized structures
315 * fit less than 8 times (see [4]) into 4KB pages.
316 * we allow very small page sizes here, to reduce wastage in
317 * threads if only small allocations are required (this does
318 * bear the risk of incresing allocation times and fragmentation
321 allocator->min_page_size = MAX (allocator->min_page_size, 4096);
322 allocator->max_page_size = MAX (allocator->min_page_size, 8192);
323 allocator->min_page_size = MIN (allocator->min_page_size, 128);
325 /* we can only align to system page size */
326 allocator->max_page_size = sys_page_size;
328 allocator->magazine_mutex = NULL; /* _g_slice_thread_init_nomessage() */
329 allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator));
330 allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator));
331 allocator->mutex_counter = 0;
332 allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
333 allocator->last_stamp = 0;
334 allocator->slab_mutex = NULL; /* _g_slice_thread_init_nomessage() */
335 allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
336 allocator->color_accu = 0;
337 magazine_cache_update_stamp();
338 /* values cached for performance reasons */
339 allocator->max_slab_chunk_size_for_magazine_cache = MAX_SLAB_CHUNK_SIZE (allocator);
340 if (allocator->config.always_malloc || allocator->config.bypass_magazines)
341 allocator->max_slab_chunk_size_for_magazine_cache = 0; /* non-optimized cases */
342 /* at this point, g_mem_gc_friendly() should be initialized, this
343 * should have been accomplished by the above g_malloc/g_new calls
348 allocator_categorize (gsize aligned_chunk_size)
350 /* speed up the likely path */
351 if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
352 return 1; /* use magazine cache */
354 /* the above will fail (max_slab_chunk_size_for_magazine_cache == 0) if the
355 * allocator is still uninitialized, or if we are not configured to use the
359 g_slice_init_nomessage ();
360 if (!allocator->config.always_malloc &&
361 aligned_chunk_size &&
362 aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
364 if (allocator->config.bypass_magazines)
365 return 2; /* use slab allocator, see [2] */
366 return 1; /* use magazine cache */
368 return 0; /* use malloc() */
372 _g_slice_thread_init_nomessage (void)
374 /* we may not use g_error() or friends here */
377 /* mem_error ("g_thread_init() must be called before GSlice is used, memory corrupted..."); */
378 fputs ("\n***MEMORY-WARNING***: ", stderr);
379 const char *pname = g_get_prgname();
380 fprintf (stderr, "%s[%u]: GSlice: ", pname ? pname : "", getpid());
381 fputs ("g_thread_init() must be called before all other GLib functions; "
382 "memory corruption due to late invocation of g_thread_init() has been detected; "
383 "this program is likely to crash, leak or unexpectedly abort soon...\n", stderr);
386 g_slice_init_nomessage();
387 private_thread_memory = g_private_new (private_thread_memory_cleanup);
388 allocator->magazine_mutex = g_mutex_new();
389 allocator->slab_mutex = g_mutex_new();
390 if (allocator->config.debug_blocks)
391 smc_tree_mutex = g_mutex_new();
395 g_mutex_lock_a (GMutex *mutex,
396 guint *contention_counter)
398 gboolean contention = FALSE;
399 if (!g_mutex_trylock (mutex))
401 g_mutex_lock (mutex);
406 allocator->mutex_counter++;
407 if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
409 allocator->mutex_counter = 0;
410 *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
413 else /* !contention */
415 allocator->mutex_counter--;
416 if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
418 allocator->mutex_counter = 0;
419 *contention_counter = MAX (*contention_counter, 1) - 1;
424 static inline ThreadMemory*
425 thread_memory_from_self (void)
427 ThreadMemory *tmem = g_private_get (private_thread_memory);
428 if (G_UNLIKELY (!tmem))
430 const guint n_magazines = MAX_SLAB_INDEX (allocator);
431 tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
432 tmem->magazine1 = (Magazine*) (tmem + 1);
433 tmem->magazine2 = &tmem->magazine1[n_magazines];
434 g_private_set (private_thread_memory, tmem);
439 static inline ChunkLink*
440 magazine_chain_pop_head (ChunkLink **magazine_chunks)
442 /* magazine chains are linked via ChunkLink->next.
443 * each ChunkLink->data of the toplevel chain may point to a subchain,
444 * linked via ChunkLink->next. ChunkLink->data of the subchains just
445 * contains uninitialized junk.
447 ChunkLink *chunk = (*magazine_chunks)->data;
448 if (G_UNLIKELY (chunk))
450 /* allocating from freed list */
451 (*magazine_chunks)->data = chunk->next;
455 chunk = *magazine_chunks;
456 *magazine_chunks = chunk->next;
461 #if 0 /* useful for debugging */
463 magazine_count (ChunkLink *head)
470 ChunkLink *child = head->data;
472 for (child = head->data; child; child = child->next)
481 allocator_get_magazine_threshold (Allocator *allocator,
484 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
485 * which is required by the implementation. also, for moderately sized chunks
486 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
487 * of chunks available per page/2 to avoid excessive traffic in the magazine
488 * cache for small to medium sized structures.
489 * the upper bound of the magazine size is effectively provided by
490 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
491 * the content of a single magazine doesn't exceed ca. 16KB.
493 gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
494 guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
495 guint contention_counter = allocator->contention_counters[ix];
496 if (G_UNLIKELY (contention_counter)) /* single CPU bias */
498 /* adapt contention counter thresholds to chunk sizes */
499 contention_counter = contention_counter * 64 / chunk_size;
500 threshold = MAX (threshold, contention_counter);
505 /* --- magazine cache --- */
507 magazine_cache_update_stamp (void)
509 if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
512 g_get_current_time (&tv);
513 allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000; /* milli seconds */
514 allocator->stamp_counter = 0;
517 allocator->stamp_counter++;
520 static inline ChunkLink*
521 magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
527 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
528 /* ensure a magazine with at least 4 unused data pointers */
529 chunk1 = magazine_chain_pop_head (&magazine_chunks);
530 chunk2 = magazine_chain_pop_head (&magazine_chunks);
531 chunk3 = magazine_chain_pop_head (&magazine_chunks);
532 chunk4 = magazine_chain_pop_head (&magazine_chunks);
533 chunk4->next = magazine_chunks;
534 chunk3->next = chunk4;
535 chunk2->next = chunk3;
536 chunk1->next = chunk2;
540 /* access the first 3 fields of a specially prepared magazine chain */
541 #define magazine_chain_prev(mc) ((mc)->data)
542 #define magazine_chain_stamp(mc) ((mc)->next->data)
543 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
544 #define magazine_chain_next(mc) ((mc)->next->next->data)
545 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
548 magazine_cache_trim (Allocator *allocator,
552 /* g_mutex_lock (allocator->mutex); done by caller */
553 /* trim magazine cache from tail */
554 ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
555 ChunkLink *trash = NULL;
556 while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator->config.working_set_msecs)
559 ChunkLink *prev = magazine_chain_prev (current);
560 ChunkLink *next = magazine_chain_next (current);
561 magazine_chain_next (prev) = next;
562 magazine_chain_prev (next) = prev;
563 /* clear special fields, put on trash stack */
564 magazine_chain_next (current) = NULL;
565 magazine_chain_count (current) = NULL;
566 magazine_chain_stamp (current) = NULL;
567 magazine_chain_prev (current) = trash;
569 /* fixup list head if required */
570 if (current == allocator->magazines[ix])
572 allocator->magazines[ix] = NULL;
577 g_mutex_unlock (allocator->magazine_mutex);
581 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
582 g_mutex_lock (allocator->slab_mutex);
586 trash = magazine_chain_prev (current);
587 magazine_chain_prev (current) = NULL; /* clear special field */
590 ChunkLink *chunk = magazine_chain_pop_head (¤t);
591 slab_allocator_free_chunk (chunk_size, chunk);
594 g_mutex_unlock (allocator->slab_mutex);
599 magazine_cache_push_magazine (guint ix,
600 ChunkLink *magazine_chunks,
601 gsize count) /* must be >= MIN_MAGAZINE_SIZE */
603 ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
604 ChunkLink *next, *prev;
605 g_mutex_lock (allocator->magazine_mutex);
606 /* add magazine at head */
607 next = allocator->magazines[ix];
609 prev = magazine_chain_prev (next);
611 next = prev = current;
612 magazine_chain_next (prev) = current;
613 magazine_chain_prev (next) = current;
614 magazine_chain_prev (current) = prev;
615 magazine_chain_next (current) = next;
616 magazine_chain_count (current) = (gpointer) count;
618 magazine_cache_update_stamp();
619 magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
620 allocator->magazines[ix] = current;
621 /* free old magazines beyond a certain threshold */
622 magazine_cache_trim (allocator, ix, allocator->last_stamp);
623 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
627 magazine_cache_pop_magazine (guint ix,
630 g_mutex_lock_a (allocator->magazine_mutex, &allocator->contention_counters[ix]);
631 if (!allocator->magazines[ix])
633 guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
634 gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
635 ChunkLink *chunk, *head;
636 g_mutex_unlock (allocator->magazine_mutex);
637 g_mutex_lock (allocator->slab_mutex);
638 head = slab_allocator_alloc_chunk (chunk_size);
641 for (i = 1; i < magazine_threshold; i++)
643 chunk->next = slab_allocator_alloc_chunk (chunk_size);
648 g_mutex_unlock (allocator->slab_mutex);
654 ChunkLink *current = allocator->magazines[ix];
655 ChunkLink *prev = magazine_chain_prev (current);
656 ChunkLink *next = magazine_chain_next (current);
658 magazine_chain_next (prev) = next;
659 magazine_chain_prev (next) = prev;
660 allocator->magazines[ix] = next == current ? NULL : next;
661 g_mutex_unlock (allocator->magazine_mutex);
662 /* clear special fields and hand out */
663 *countp = (gsize) magazine_chain_count (current);
664 magazine_chain_prev (current) = NULL;
665 magazine_chain_next (current) = NULL;
666 magazine_chain_count (current) = NULL;
667 magazine_chain_stamp (current) = NULL;
672 /* --- thread magazines --- */
674 private_thread_memory_cleanup (gpointer data)
676 ThreadMemory *tmem = data;
677 const guint n_magazines = MAX_SLAB_INDEX (allocator);
679 for (ix = 0; ix < n_magazines; ix++)
683 mags[0] = &tmem->magazine1[ix];
684 mags[1] = &tmem->magazine2[ix];
685 for (j = 0; j < 2; j++)
687 Magazine *mag = mags[j];
688 if (mag->count >= MIN_MAGAZINE_SIZE)
689 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
692 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
693 g_mutex_lock (allocator->slab_mutex);
696 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
697 slab_allocator_free_chunk (chunk_size, chunk);
699 g_mutex_unlock (allocator->slab_mutex);
707 thread_memory_magazine1_reload (ThreadMemory *tmem,
710 Magazine *mag = &tmem->magazine1[ix];
711 mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
713 mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
717 thread_memory_magazine2_unload (ThreadMemory *tmem,
720 Magazine *mag = &tmem->magazine2[ix];
721 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
727 thread_memory_swap_magazines (ThreadMemory *tmem,
730 Magazine xmag = tmem->magazine1[ix];
731 tmem->magazine1[ix] = tmem->magazine2[ix];
732 tmem->magazine2[ix] = xmag;
735 static inline gboolean
736 thread_memory_magazine1_is_empty (ThreadMemory *tmem,
739 return tmem->magazine1[ix].chunks == NULL;
742 static inline gboolean
743 thread_memory_magazine2_is_full (ThreadMemory *tmem,
746 return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
749 static inline gpointer
750 thread_memory_magazine1_alloc (ThreadMemory *tmem,
753 Magazine *mag = &tmem->magazine1[ix];
754 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
755 if (G_LIKELY (mag->count > 0))
761 thread_memory_magazine2_free (ThreadMemory *tmem,
765 Magazine *mag = &tmem->magazine2[ix];
766 ChunkLink *chunk = mem;
768 chunk->next = mag->chunks;
773 /* --- API functions --- */
775 g_slice_alloc (gsize mem_size)
780 chunk_size = P2ALIGN (mem_size);
781 acat = allocator_categorize (chunk_size);
782 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
784 ThreadMemory *tmem = thread_memory_from_self();
785 guint ix = SLAB_INDEX (allocator, chunk_size);
786 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
788 thread_memory_swap_magazines (tmem, ix);
789 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
790 thread_memory_magazine1_reload (tmem, ix);
792 mem = thread_memory_magazine1_alloc (tmem, ix);
794 else if (acat == 2) /* allocate through slab allocator */
796 g_mutex_lock (allocator->slab_mutex);
797 mem = slab_allocator_alloc_chunk (chunk_size);
798 g_mutex_unlock (allocator->slab_mutex);
800 else /* delegate to system malloc */
801 mem = g_malloc (mem_size);
802 if (G_UNLIKELY (allocator->config.debug_blocks))
803 smc_notify_alloc (mem, mem_size);
808 g_slice_alloc0 (gsize mem_size)
810 gpointer mem = g_slice_alloc (mem_size);
812 memset (mem, 0, mem_size);
817 g_slice_free1 (gsize mem_size,
820 gsize chunk_size = P2ALIGN (mem_size);
821 guint acat = allocator_categorize (chunk_size);
822 if (G_UNLIKELY (!mem_block))
824 if (G_UNLIKELY (allocator->config.debug_blocks) &&
825 !smc_notify_free (mem_block, mem_size))
827 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
829 ThreadMemory *tmem = thread_memory_from_self();
830 guint ix = SLAB_INDEX (allocator, chunk_size);
831 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
833 thread_memory_swap_magazines (tmem, ix);
834 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
835 thread_memory_magazine2_unload (tmem, ix);
837 if (G_UNLIKELY (g_mem_gc_friendly))
838 memset (mem_block, 0, chunk_size);
839 thread_memory_magazine2_free (tmem, ix, mem_block);
841 else if (acat == 2) /* allocate through slab allocator */
843 if (G_UNLIKELY (g_mem_gc_friendly))
844 memset (mem_block, 0, chunk_size);
845 g_mutex_lock (allocator->slab_mutex);
846 slab_allocator_free_chunk (chunk_size, mem_block);
847 g_mutex_unlock (allocator->slab_mutex);
849 else /* delegate to system malloc */
851 if (G_UNLIKELY (g_mem_gc_friendly))
852 memset (mem_block, 0, mem_size);
858 g_slice_free_chain_with_offset (gsize mem_size,
862 gpointer slice = mem_chain;
863 /* while the thread magazines and the magazine cache are implemented so that
864 * they can easily be extended to allow for free lists containing more free
865 * lists for the first level nodes, which would allow O(1) freeing in this
866 * function, the benefit of such an extension is questionable, because:
867 * - the magazine size counts will become mere lower bounds which confuses
868 * the code adapting to lock contention;
869 * - freeing a single node to the thread magazines is very fast, so this
870 * O(list_length) operation is multiplied by a fairly small factor;
871 * - memory usage histograms on larger applications seem to indicate that
872 * the amount of released multi node lists is negligible in comparison
873 * to single node releases.
874 * - the major performance bottle neck, namely g_private_get() or
875 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
876 * inner loop for freeing chained slices.
878 gsize chunk_size = P2ALIGN (mem_size);
879 guint acat = allocator_categorize (chunk_size);
880 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
882 ThreadMemory *tmem = thread_memory_from_self();
883 guint ix = SLAB_INDEX (allocator, chunk_size);
886 guint8 *current = slice;
887 slice = *(gpointer*) (current + next_offset);
888 if (G_UNLIKELY (allocator->config.debug_blocks) &&
889 !smc_notify_free (current, mem_size))
891 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
893 thread_memory_swap_magazines (tmem, ix);
894 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
895 thread_memory_magazine2_unload (tmem, ix);
897 if (G_UNLIKELY (g_mem_gc_friendly))
898 memset (current, 0, chunk_size);
899 thread_memory_magazine2_free (tmem, ix, current);
902 else if (acat == 2) /* allocate through slab allocator */
904 g_mutex_lock (allocator->slab_mutex);
907 guint8 *current = slice;
908 slice = *(gpointer*) (current + next_offset);
909 if (G_UNLIKELY (allocator->config.debug_blocks) &&
910 !smc_notify_free (current, mem_size))
912 if (G_UNLIKELY (g_mem_gc_friendly))
913 memset (current, 0, chunk_size);
914 slab_allocator_free_chunk (chunk_size, current);
916 g_mutex_unlock (allocator->slab_mutex);
918 else /* delegate to system malloc */
921 guint8 *current = slice;
922 slice = *(gpointer*) (current + next_offset);
923 if (G_UNLIKELY (allocator->config.debug_blocks) &&
924 !smc_notify_free (current, mem_size))
926 if (G_UNLIKELY (g_mem_gc_friendly))
927 memset (current, 0, mem_size);
932 /* --- single page allocator --- */
934 allocator_slab_stack_push (Allocator *allocator,
938 /* insert slab at slab ring head */
939 if (!allocator->slab_stack[ix])
946 SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
952 allocator->slab_stack[ix] = sinfo;
956 allocator_aligned_page_size (Allocator *allocator,
959 gsize val = 1 << g_bit_storage (n_bytes - 1);
960 val = MAX (val, allocator->min_page_size);
965 allocator_add_slab (Allocator *allocator,
971 gsize addr, padding, n_chunks, color = 0;
972 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
973 /* allocate 1 page for the chunks and the slab */
974 gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
975 guint8 *mem = aligned_memory;
979 const gchar *syserr = "unknown error";
981 syserr = strerror (errno);
983 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
984 (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
986 /* mask page adress */
987 addr = ((gsize) mem / page_size) * page_size;
988 /* assert alignment */
989 mem_assert (aligned_memory == (gpointer) addr);
990 /* basic slab info setup */
991 sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
992 sinfo->n_allocated = 0;
993 sinfo->chunks = NULL;
994 /* figure cache colorization */
995 n_chunks = ((guint8*) sinfo - mem) / chunk_size;
996 padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
999 color = (allocator->color_accu * P2ALIGNMENT) % padding;
1000 allocator->color_accu += allocator->config.color_increment;
1002 /* add chunks to free list */
1003 chunk = (ChunkLink*) (mem + color);
1004 sinfo->chunks = chunk;
1005 for (i = 0; i < n_chunks - 1; i++)
1007 chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
1008 chunk = chunk->next;
1010 chunk->next = NULL; /* last chunk */
1011 /* add slab to slab ring */
1012 allocator_slab_stack_push (allocator, ix, sinfo);
1016 slab_allocator_alloc_chunk (gsize chunk_size)
1019 guint ix = SLAB_INDEX (allocator, chunk_size);
1020 /* ensure non-empty slab */
1021 if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
1022 allocator_add_slab (allocator, ix, chunk_size);
1023 /* allocate chunk */
1024 chunk = allocator->slab_stack[ix]->chunks;
1025 allocator->slab_stack[ix]->chunks = chunk->next;
1026 allocator->slab_stack[ix]->n_allocated++;
1027 /* rotate empty slabs */
1028 if (!allocator->slab_stack[ix]->chunks)
1029 allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
1034 slab_allocator_free_chunk (gsize chunk_size,
1039 guint ix = SLAB_INDEX (allocator, chunk_size);
1040 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1041 gsize addr = ((gsize) mem / page_size) * page_size;
1042 /* mask page adress */
1043 guint8 *page = (guint8*) addr;
1044 SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
1045 /* assert valid chunk count */
1046 mem_assert (sinfo->n_allocated > 0);
1047 /* add chunk to free list */
1048 was_empty = sinfo->chunks == NULL;
1049 chunk = (ChunkLink*) mem;
1050 chunk->next = sinfo->chunks;
1051 sinfo->chunks = chunk;
1052 sinfo->n_allocated--;
1053 /* keep slab ring partially sorted, empty slabs at end */
1057 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1060 if (allocator->slab_stack[ix] == sinfo)
1061 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1062 /* insert slab at head */
1063 allocator_slab_stack_push (allocator, ix, sinfo);
1065 /* eagerly free complete unused slabs */
1066 if (!sinfo->n_allocated)
1069 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1072 if (allocator->slab_stack[ix] == sinfo)
1073 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1075 allocator_memfree (page_size, page);
1079 /* --- memalign implementation --- */
1080 #ifdef HAVE_MALLOC_H
1081 #include <malloc.h> /* memalign() */
1085 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1086 * define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
1087 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1088 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1089 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1092 #if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1093 static GTrashStack *compat_valloc_trash = NULL;
1097 allocator_memalign (gsize alignment,
1100 gpointer aligned_memory = NULL;
1102 #if HAVE_COMPLIANT_POSIX_MEMALIGN
1103 err = posix_memalign (&aligned_memory, alignment, memsize);
1106 aligned_memory = memalign (alignment, memsize);
1110 aligned_memory = valloc (memsize);
1113 /* simplistic non-freeing page allocator */
1114 mem_assert (alignment == sys_page_size);
1115 mem_assert (memsize <= sys_page_size);
1116 if (!compat_valloc_trash)
1118 const guint n_pages = 16;
1119 guint8 *mem = malloc (n_pages * sys_page_size);
1124 guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
1126 i--; /* mem wasn't page aligned */
1128 g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
1131 aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
1133 if (!aligned_memory)
1135 return aligned_memory;
1139 allocator_memfree (gsize memsize,
1142 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1145 mem_assert (memsize <= sys_page_size);
1146 g_trash_stack_push (&compat_valloc_trash, mem);
1151 mem_error (const char *format,
1156 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1157 fputs ("\n***MEMORY-ERROR***: ", stderr);
1158 pname = g_get_prgname();
1159 fprintf (stderr, "%s[%u]: GSlice: ", pname ? pname : "", getpid());
1160 va_start (args, format);
1161 vfprintf (stderr, format, args);
1163 fputs ("\n", stderr);
1168 /* --- g-slice memory checker tree --- */
1169 typedef size_t SmcKType; /* key type */
1170 typedef size_t SmcVType; /* value type */
1175 static void smc_tree_insert (SmcKType key,
1177 static gboolean smc_tree_lookup (SmcKType key,
1179 static gboolean smc_tree_remove (SmcKType key);
1182 /* --- g-slice memory checker implementation --- */
1184 smc_notify_alloc (void *pointer,
1187 size_t adress = (size_t) pointer;
1189 smc_tree_insert (adress, size);
1194 smc_notify_ignore (void *pointer)
1196 size_t adress = (size_t) pointer;
1198 smc_tree_remove (adress);
1203 smc_notify_free (void *pointer,
1206 size_t adress = (size_t) pointer;
1208 return 1; /* ignore */
1210 gboolean found_one = smc_tree_lookup (adress, &real_size);
1213 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%zu\n", pointer, size);
1216 if (real_size != size && (real_size || size))
1218 fprintf (stderr, "GSlice: MemChecker: attempt to release block with invalid size: %p size=%zu invalid-size=%zu\n", pointer, real_size, size);
1221 if (!smc_tree_remove (adress))
1223 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%zu\n", pointer, size);
1226 return 1; /* all fine */
1229 /* --- g-slice memory checker tree implementation --- */
1230 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1231 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1232 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key adress space per trunk, should distribute uniformly across BRANCH_COUNT */
1233 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1234 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1238 unsigned int n_entries;
1241 static SmcBranch **smc_tree_root = NULL;
1244 smc_tree_abort (int errval)
1246 const char *syserr = "unknown error";
1248 syserr = strerror (errval);
1250 mem_error ("MemChecker: failure in debugging tree: %s", syserr);
1253 static inline SmcEntry*
1254 smc_tree_branch_grow_L (SmcBranch *branch,
1257 unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
1258 unsigned int new_size = old_size + sizeof (branch->entries[0]);
1260 mem_assert (index <= branch->n_entries);
1261 branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
1262 if (!branch->entries)
1263 smc_tree_abort (errno);
1264 entry = branch->entries + index;
1265 g_memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
1266 branch->n_entries += 1;
1270 static inline SmcEntry*
1271 smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
1274 unsigned int n_nodes = branch->n_entries, offs = 0;
1275 SmcEntry *check = branch->entries;
1277 while (offs < n_nodes)
1279 unsigned int i = (offs + n_nodes) >> 1;
1280 check = branch->entries + i;
1281 cmp = key < check->key ? -1 : key != check->key;
1283 return check; /* return exact match */
1286 else /* (cmp > 0) */
1289 /* check points at last mismatch, cmp > 0 indicates greater key */
1290 return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
1294 smc_tree_insert (SmcKType key,
1297 g_mutex_lock (smc_tree_mutex);
1298 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1301 smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
1303 smc_tree_abort (errno);
1305 if (!smc_tree_root[ix0])
1307 smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
1308 if (!smc_tree_root[ix0])
1309 smc_tree_abort (errno);
1311 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1312 if (!entry || /* need create */
1313 entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
1314 entry->key != key) /* need insert */
1315 entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
1317 entry->value = value;
1318 g_mutex_unlock (smc_tree_mutex);
1322 smc_tree_lookup (SmcKType key,
1325 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1326 gboolean found_one = FALSE;
1328 g_mutex_lock (smc_tree_mutex);
1329 SmcEntry *entry = NULL;
1330 if (smc_tree_root && smc_tree_root[ix0])
1332 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1334 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1338 *value_p = entry->value;
1341 g_mutex_unlock (smc_tree_mutex);
1346 smc_tree_remove (SmcKType key)
1348 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1349 gboolean found_one = FALSE;
1350 g_mutex_lock (smc_tree_mutex);
1351 if (smc_tree_root && smc_tree_root[ix0])
1353 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1355 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1358 unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
1359 smc_tree_root[ix0][ix1].n_entries -= 1;
1360 g_memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
1361 if (!smc_tree_root[ix0][ix1].n_entries)
1363 /* avoid useless pressure on the memory system */
1364 free (smc_tree_root[ix0][ix1].entries);
1365 smc_tree_root[ix0][ix1].entries = NULL;
1370 g_mutex_unlock (smc_tree_mutex);
1374 #ifdef G_ENABLE_DEBUG
1376 g_slice_debug_tree_statistics (void)
1378 g_mutex_lock (smc_tree_mutex);
1381 unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
1383 for (i = 0; i < SMC_TRUNK_COUNT; i++)
1384 if (smc_tree_root[i])
1387 for (j = 0; j < SMC_BRANCH_COUNT; j++)
1388 if (smc_tree_root[i][j].n_entries)
1391 su += smc_tree_root[i][j].n_entries;
1392 en = MIN (en, smc_tree_root[i][j].n_entries);
1393 ex = MAX (ex, smc_tree_root[i][j].n_entries);
1395 else if (smc_tree_root[i][j].entries)
1396 o++; /* formerly used, now empty */
1399 tf = MAX (t, 1.0); // max(1) to be a valid divisor
1400 bf = MAX (b, 1.0); // max(1) to be a valid divisor
1401 fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
1402 fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1404 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
1405 fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1409 fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
1410 g_mutex_unlock (smc_tree_mutex);
1412 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1413 * PID %CPU %MEM VSZ RSS COMMAND
1414 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1415 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1416 * 114017 103714 2354 344 0 108676 0
1417 * $ cat /proc/8887/status
1428 * (gdb) print g_slice_debug_tree_statistics ()
1429 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1430 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1431 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1434 #endif /* G_ENABLE_DEBUG */
1436 #define __G_SLICE_C__
1437 #include "galiasdef.c"