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; /* 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 */
362 allocator_categorize (gsize aligned_chunk_size)
364 GLIB_ENSURE_CTOR (g_slice_init_nomessage);
366 /* speed up the likely path */
367 if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
368 return 1; /* use magazine cache */
370 if (!allocator->config.always_malloc &&
371 aligned_chunk_size &&
372 aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
374 if (allocator->config.bypass_magazines)
375 return 2; /* use slab allocator, see [2] */
376 return 1; /* use magazine cache */
378 return 0; /* use malloc() */
382 g_mutex_lock_a (GMutex *mutex,
383 guint *contention_counter)
385 gboolean contention = FALSE;
386 if (!g_mutex_trylock (mutex))
388 g_mutex_lock (mutex);
393 allocator->mutex_counter++;
394 if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
396 allocator->mutex_counter = 0;
397 *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
400 else /* !contention */
402 allocator->mutex_counter--;
403 if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
405 allocator->mutex_counter = 0;
406 *contention_counter = MAX (*contention_counter, 1) - 1;
411 static inline ThreadMemory*
412 thread_memory_from_self (void)
414 ThreadMemory *tmem = g_private_get (&private_thread_memory);
415 if (G_UNLIKELY (!tmem))
417 const guint n_magazines = MAX_SLAB_INDEX (allocator);
418 tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
419 tmem->magazine1 = (Magazine*) (tmem + 1);
420 tmem->magazine2 = &tmem->magazine1[n_magazines];
421 g_private_set (&private_thread_memory, tmem);
426 static inline ChunkLink*
427 magazine_chain_pop_head (ChunkLink **magazine_chunks)
429 /* magazine chains are linked via ChunkLink->next.
430 * each ChunkLink->data of the toplevel chain may point to a subchain,
431 * linked via ChunkLink->next. ChunkLink->data of the subchains just
432 * contains uninitialized junk.
434 ChunkLink *chunk = (*magazine_chunks)->data;
435 if (G_UNLIKELY (chunk))
437 /* allocating from freed list */
438 (*magazine_chunks)->data = chunk->next;
442 chunk = *magazine_chunks;
443 *magazine_chunks = chunk->next;
448 #if 0 /* useful for debugging */
450 magazine_count (ChunkLink *head)
457 ChunkLink *child = head->data;
459 for (child = head->data; child; child = child->next)
468 allocator_get_magazine_threshold (Allocator *allocator,
471 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
472 * which is required by the implementation. also, for moderately sized chunks
473 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
474 * of chunks available per page/2 to avoid excessive traffic in the magazine
475 * cache for small to medium sized structures.
476 * the upper bound of the magazine size is effectively provided by
477 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
478 * the content of a single magazine doesn't exceed ca. 16KB.
480 gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
481 guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
482 guint contention_counter = allocator->contention_counters[ix];
483 if (G_UNLIKELY (contention_counter)) /* single CPU bias */
485 /* adapt contention counter thresholds to chunk sizes */
486 contention_counter = contention_counter * 64 / chunk_size;
487 threshold = MAX (threshold, contention_counter);
492 /* --- magazine cache --- */
494 magazine_cache_update_stamp (void)
496 if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
499 g_get_current_time (&tv);
500 allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 1000; /* milli seconds */
501 allocator->stamp_counter = 0;
504 allocator->stamp_counter++;
507 static inline ChunkLink*
508 magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
514 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
515 /* ensure a magazine with at least 4 unused data pointers */
516 chunk1 = magazine_chain_pop_head (&magazine_chunks);
517 chunk2 = magazine_chain_pop_head (&magazine_chunks);
518 chunk3 = magazine_chain_pop_head (&magazine_chunks);
519 chunk4 = magazine_chain_pop_head (&magazine_chunks);
520 chunk4->next = magazine_chunks;
521 chunk3->next = chunk4;
522 chunk2->next = chunk3;
523 chunk1->next = chunk2;
527 /* access the first 3 fields of a specially prepared magazine chain */
528 #define magazine_chain_prev(mc) ((mc)->data)
529 #define magazine_chain_stamp(mc) ((mc)->next->data)
530 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
531 #define magazine_chain_next(mc) ((mc)->next->next->data)
532 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
535 magazine_cache_trim (Allocator *allocator,
539 /* g_mutex_lock (allocator->mutex); done by caller */
540 /* trim magazine cache from tail */
541 ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
542 ChunkLink *trash = NULL;
543 while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator->config.working_set_msecs)
546 ChunkLink *prev = magazine_chain_prev (current);
547 ChunkLink *next = magazine_chain_next (current);
548 magazine_chain_next (prev) = next;
549 magazine_chain_prev (next) = prev;
550 /* clear special fields, put on trash stack */
551 magazine_chain_next (current) = NULL;
552 magazine_chain_count (current) = NULL;
553 magazine_chain_stamp (current) = NULL;
554 magazine_chain_prev (current) = trash;
556 /* fixup list head if required */
557 if (current == allocator->magazines[ix])
559 allocator->magazines[ix] = NULL;
564 g_mutex_unlock (&allocator->magazine_mutex);
568 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
569 g_mutex_lock (&allocator->slab_mutex);
573 trash = magazine_chain_prev (current);
574 magazine_chain_prev (current) = NULL; /* clear special field */
577 ChunkLink *chunk = magazine_chain_pop_head (¤t);
578 slab_allocator_free_chunk (chunk_size, chunk);
581 g_mutex_unlock (&allocator->slab_mutex);
586 magazine_cache_push_magazine (guint ix,
587 ChunkLink *magazine_chunks,
588 gsize count) /* must be >= MIN_MAGAZINE_SIZE */
590 ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
591 ChunkLink *next, *prev;
592 g_mutex_lock (&allocator->magazine_mutex);
593 /* add magazine at head */
594 next = allocator->magazines[ix];
596 prev = magazine_chain_prev (next);
598 next = prev = current;
599 magazine_chain_next (prev) = current;
600 magazine_chain_prev (next) = current;
601 magazine_chain_prev (current) = prev;
602 magazine_chain_next (current) = next;
603 magazine_chain_count (current) = (gpointer) count;
605 magazine_cache_update_stamp();
606 magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
607 allocator->magazines[ix] = current;
608 /* free old magazines beyond a certain threshold */
609 magazine_cache_trim (allocator, ix, allocator->last_stamp);
610 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
614 magazine_cache_pop_magazine (guint ix,
617 g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]);
618 if (!allocator->magazines[ix])
620 guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
621 gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
622 ChunkLink *chunk, *head;
623 g_mutex_unlock (&allocator->magazine_mutex);
624 g_mutex_lock (&allocator->slab_mutex);
625 head = slab_allocator_alloc_chunk (chunk_size);
628 for (i = 1; i < magazine_threshold; i++)
630 chunk->next = slab_allocator_alloc_chunk (chunk_size);
635 g_mutex_unlock (&allocator->slab_mutex);
641 ChunkLink *current = allocator->magazines[ix];
642 ChunkLink *prev = magazine_chain_prev (current);
643 ChunkLink *next = magazine_chain_next (current);
645 magazine_chain_next (prev) = next;
646 magazine_chain_prev (next) = prev;
647 allocator->magazines[ix] = next == current ? NULL : next;
648 g_mutex_unlock (&allocator->magazine_mutex);
649 /* clear special fields and hand out */
650 *countp = (gsize) magazine_chain_count (current);
651 magazine_chain_prev (current) = NULL;
652 magazine_chain_next (current) = NULL;
653 magazine_chain_count (current) = NULL;
654 magazine_chain_stamp (current) = NULL;
659 /* --- thread magazines --- */
661 private_thread_memory_cleanup (gpointer data)
663 ThreadMemory *tmem = data;
664 const guint n_magazines = MAX_SLAB_INDEX (allocator);
666 for (ix = 0; ix < n_magazines; ix++)
670 mags[0] = &tmem->magazine1[ix];
671 mags[1] = &tmem->magazine2[ix];
672 for (j = 0; j < 2; j++)
674 Magazine *mag = mags[j];
675 if (mag->count >= MIN_MAGAZINE_SIZE)
676 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
679 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
680 g_mutex_lock (&allocator->slab_mutex);
683 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
684 slab_allocator_free_chunk (chunk_size, chunk);
686 g_mutex_unlock (&allocator->slab_mutex);
694 thread_memory_magazine1_reload (ThreadMemory *tmem,
697 Magazine *mag = &tmem->magazine1[ix];
698 mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
700 mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
704 thread_memory_magazine2_unload (ThreadMemory *tmem,
707 Magazine *mag = &tmem->magazine2[ix];
708 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
714 thread_memory_swap_magazines (ThreadMemory *tmem,
717 Magazine xmag = tmem->magazine1[ix];
718 tmem->magazine1[ix] = tmem->magazine2[ix];
719 tmem->magazine2[ix] = xmag;
722 static inline gboolean
723 thread_memory_magazine1_is_empty (ThreadMemory *tmem,
726 return tmem->magazine1[ix].chunks == NULL;
729 static inline gboolean
730 thread_memory_magazine2_is_full (ThreadMemory *tmem,
733 return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
736 static inline gpointer
737 thread_memory_magazine1_alloc (ThreadMemory *tmem,
740 Magazine *mag = &tmem->magazine1[ix];
741 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
742 if (G_LIKELY (mag->count > 0))
748 thread_memory_magazine2_free (ThreadMemory *tmem,
752 Magazine *mag = &tmem->magazine2[ix];
753 ChunkLink *chunk = mem;
755 chunk->next = mag->chunks;
760 /* --- API functions --- */
762 g_slice_alloc (gsize mem_size)
767 chunk_size = P2ALIGN (mem_size);
768 acat = allocator_categorize (chunk_size);
769 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
771 ThreadMemory *tmem = thread_memory_from_self();
772 guint ix = SLAB_INDEX (allocator, chunk_size);
773 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
775 thread_memory_swap_magazines (tmem, ix);
776 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
777 thread_memory_magazine1_reload (tmem, ix);
779 mem = thread_memory_magazine1_alloc (tmem, ix);
781 else if (acat == 2) /* allocate through slab allocator */
783 g_mutex_lock (&allocator->slab_mutex);
784 mem = slab_allocator_alloc_chunk (chunk_size);
785 g_mutex_unlock (&allocator->slab_mutex);
787 else /* delegate to system malloc */
788 mem = g_malloc (mem_size);
789 if (G_UNLIKELY (allocator->config.debug_blocks))
790 smc_notify_alloc (mem, mem_size);
792 TRACE (GLIB_SLICE_ALLOC((void*)mem, mem_size));
798 g_slice_alloc0 (gsize mem_size)
800 gpointer mem = g_slice_alloc (mem_size);
802 memset (mem, 0, mem_size);
807 g_slice_copy (gsize mem_size,
808 gconstpointer mem_block)
810 gpointer mem = g_slice_alloc (mem_size);
812 memcpy (mem, mem_block, 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);
855 TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size));
859 g_slice_free_chain_with_offset (gsize mem_size,
863 gpointer slice = mem_chain;
864 /* while the thread magazines and the magazine cache are implemented so that
865 * they can easily be extended to allow for free lists containing more free
866 * lists for the first level nodes, which would allow O(1) freeing in this
867 * function, the benefit of such an extension is questionable, because:
868 * - the magazine size counts will become mere lower bounds which confuses
869 * the code adapting to lock contention;
870 * - freeing a single node to the thread magazines is very fast, so this
871 * O(list_length) operation is multiplied by a fairly small factor;
872 * - memory usage histograms on larger applications seem to indicate that
873 * the amount of released multi node lists is negligible in comparison
874 * to single node releases.
875 * - the major performance bottle neck, namely g_private_get() or
876 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
877 * inner loop for freeing chained slices.
879 gsize chunk_size = P2ALIGN (mem_size);
880 guint acat = allocator_categorize (chunk_size);
881 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
883 ThreadMemory *tmem = thread_memory_from_self();
884 guint ix = SLAB_INDEX (allocator, chunk_size);
887 guint8 *current = slice;
888 slice = *(gpointer*) (current + next_offset);
889 if (G_UNLIKELY (allocator->config.debug_blocks) &&
890 !smc_notify_free (current, mem_size))
892 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
894 thread_memory_swap_magazines (tmem, ix);
895 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
896 thread_memory_magazine2_unload (tmem, ix);
898 if (G_UNLIKELY (g_mem_gc_friendly))
899 memset (current, 0, chunk_size);
900 thread_memory_magazine2_free (tmem, ix, current);
903 else if (acat == 2) /* allocate through slab allocator */
905 g_mutex_lock (&allocator->slab_mutex);
908 guint8 *current = slice;
909 slice = *(gpointer*) (current + next_offset);
910 if (G_UNLIKELY (allocator->config.debug_blocks) &&
911 !smc_notify_free (current, mem_size))
913 if (G_UNLIKELY (g_mem_gc_friendly))
914 memset (current, 0, chunk_size);
915 slab_allocator_free_chunk (chunk_size, current);
917 g_mutex_unlock (&allocator->slab_mutex);
919 else /* delegate to system malloc */
922 guint8 *current = slice;
923 slice = *(gpointer*) (current + next_offset);
924 if (G_UNLIKELY (allocator->config.debug_blocks) &&
925 !smc_notify_free (current, mem_size))
927 if (G_UNLIKELY (g_mem_gc_friendly))
928 memset (current, 0, mem_size);
933 /* --- single page allocator --- */
935 allocator_slab_stack_push (Allocator *allocator,
939 /* insert slab at slab ring head */
940 if (!allocator->slab_stack[ix])
947 SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
953 allocator->slab_stack[ix] = sinfo;
957 allocator_aligned_page_size (Allocator *allocator,
960 gsize val = 1 << g_bit_storage (n_bytes - 1);
961 val = MAX (val, allocator->min_page_size);
966 allocator_add_slab (Allocator *allocator,
972 gsize addr, padding, n_chunks, color = 0;
973 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
974 /* allocate 1 page for the chunks and the slab */
975 gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
976 guint8 *mem = aligned_memory;
980 const gchar *syserr = "unknown error";
982 syserr = strerror (errno);
984 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
985 (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
987 /* mask page address */
988 addr = ((gsize) mem / page_size) * page_size;
989 /* assert alignment */
990 mem_assert (aligned_memory == (gpointer) addr);
991 /* basic slab info setup */
992 sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
993 sinfo->n_allocated = 0;
994 sinfo->chunks = NULL;
995 /* figure cache colorization */
996 n_chunks = ((guint8*) sinfo - mem) / chunk_size;
997 padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
1000 color = (allocator->color_accu * P2ALIGNMENT) % padding;
1001 allocator->color_accu += allocator->config.color_increment;
1003 /* add chunks to free list */
1004 chunk = (ChunkLink*) (mem + color);
1005 sinfo->chunks = chunk;
1006 for (i = 0; i < n_chunks - 1; i++)
1008 chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
1009 chunk = chunk->next;
1011 chunk->next = NULL; /* last chunk */
1012 /* add slab to slab ring */
1013 allocator_slab_stack_push (allocator, ix, sinfo);
1017 slab_allocator_alloc_chunk (gsize chunk_size)
1020 guint ix = SLAB_INDEX (allocator, chunk_size);
1021 /* ensure non-empty slab */
1022 if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
1023 allocator_add_slab (allocator, ix, chunk_size);
1024 /* allocate chunk */
1025 chunk = allocator->slab_stack[ix]->chunks;
1026 allocator->slab_stack[ix]->chunks = chunk->next;
1027 allocator->slab_stack[ix]->n_allocated++;
1028 /* rotate empty slabs */
1029 if (!allocator->slab_stack[ix]->chunks)
1030 allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
1035 slab_allocator_free_chunk (gsize chunk_size,
1040 guint ix = SLAB_INDEX (allocator, chunk_size);
1041 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1042 gsize addr = ((gsize) mem / page_size) * page_size;
1043 /* mask page address */
1044 guint8 *page = (guint8*) addr;
1045 SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
1046 /* assert valid chunk count */
1047 mem_assert (sinfo->n_allocated > 0);
1048 /* add chunk to free list */
1049 was_empty = sinfo->chunks == NULL;
1050 chunk = (ChunkLink*) mem;
1051 chunk->next = sinfo->chunks;
1052 sinfo->chunks = chunk;
1053 sinfo->n_allocated--;
1054 /* keep slab ring partially sorted, empty slabs at end */
1058 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1061 if (allocator->slab_stack[ix] == sinfo)
1062 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1063 /* insert slab at head */
1064 allocator_slab_stack_push (allocator, ix, sinfo);
1066 /* eagerly free complete unused slabs */
1067 if (!sinfo->n_allocated)
1070 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1073 if (allocator->slab_stack[ix] == sinfo)
1074 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1076 allocator_memfree (page_size, page);
1080 /* --- memalign implementation --- */
1081 #ifdef HAVE_MALLOC_H
1082 #include <malloc.h> /* memalign() */
1086 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1087 * define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
1088 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1089 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1090 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1093 #if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1094 static GTrashStack *compat_valloc_trash = NULL;
1098 allocator_memalign (gsize alignment,
1101 gpointer aligned_memory = NULL;
1103 #if HAVE_COMPLIANT_POSIX_MEMALIGN
1104 err = posix_memalign (&aligned_memory, alignment, memsize);
1107 aligned_memory = memalign (alignment, memsize);
1111 aligned_memory = valloc (memsize);
1114 /* simplistic non-freeing page allocator */
1115 mem_assert (alignment == sys_page_size);
1116 mem_assert (memsize <= sys_page_size);
1117 if (!compat_valloc_trash)
1119 const guint n_pages = 16;
1120 guint8 *mem = malloc (n_pages * sys_page_size);
1125 guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
1127 i--; /* mem wasn't page aligned */
1129 g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
1132 aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
1134 if (!aligned_memory)
1136 return aligned_memory;
1140 allocator_memfree (gsize memsize,
1143 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1146 mem_assert (memsize <= sys_page_size);
1147 g_trash_stack_push (&compat_valloc_trash, mem);
1152 mem_error (const char *format,
1157 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1158 fputs ("\n***MEMORY-ERROR***: ", stderr);
1159 pname = g_get_prgname();
1160 fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid());
1161 va_start (args, format);
1162 vfprintf (stderr, format, args);
1164 fputs ("\n", stderr);
1169 /* --- g-slice memory checker tree --- */
1170 typedef size_t SmcKType; /* key type */
1171 typedef size_t SmcVType; /* value type */
1176 static void smc_tree_insert (SmcKType key,
1178 static gboolean smc_tree_lookup (SmcKType key,
1180 static gboolean smc_tree_remove (SmcKType key);
1183 /* --- g-slice memory checker implementation --- */
1185 smc_notify_alloc (void *pointer,
1188 size_t adress = (size_t) pointer;
1190 smc_tree_insert (adress, size);
1195 smc_notify_ignore (void *pointer)
1197 size_t adress = (size_t) pointer;
1199 smc_tree_remove (adress);
1204 smc_notify_free (void *pointer,
1207 size_t adress = (size_t) pointer;
1212 return 1; /* ignore */
1213 found_one = smc_tree_lookup (adress, &real_size);
1216 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1219 if (real_size != size && (real_size || size))
1221 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);
1224 if (!smc_tree_remove (adress))
1226 fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1229 return 1; /* all fine */
1232 /* --- g-slice memory checker tree implementation --- */
1233 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1234 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1235 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key adress space per trunk, should distribute uniformly across BRANCH_COUNT */
1236 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1237 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1241 unsigned int n_entries;
1244 static SmcBranch **smc_tree_root = NULL;
1247 smc_tree_abort (int errval)
1249 const char *syserr = "unknown error";
1251 syserr = strerror (errval);
1253 mem_error ("MemChecker: failure in debugging tree: %s", syserr);
1256 static inline SmcEntry*
1257 smc_tree_branch_grow_L (SmcBranch *branch,
1260 unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
1261 unsigned int new_size = old_size + sizeof (branch->entries[0]);
1263 mem_assert (index <= branch->n_entries);
1264 branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
1265 if (!branch->entries)
1266 smc_tree_abort (errno);
1267 entry = branch->entries + index;
1268 g_memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
1269 branch->n_entries += 1;
1273 static inline SmcEntry*
1274 smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
1277 unsigned int n_nodes = branch->n_entries, offs = 0;
1278 SmcEntry *check = branch->entries;
1280 while (offs < n_nodes)
1282 unsigned int i = (offs + n_nodes) >> 1;
1283 check = branch->entries + i;
1284 cmp = key < check->key ? -1 : key != check->key;
1286 return check; /* return exact match */
1289 else /* (cmp > 0) */
1292 /* check points at last mismatch, cmp > 0 indicates greater key */
1293 return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
1297 smc_tree_insert (SmcKType key,
1300 unsigned int ix0, ix1;
1303 g_mutex_lock (&smc_tree_mutex);
1304 ix0 = SMC_TRUNK_HASH (key);
1305 ix1 = SMC_BRANCH_HASH (key);
1308 smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
1310 smc_tree_abort (errno);
1312 if (!smc_tree_root[ix0])
1314 smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
1315 if (!smc_tree_root[ix0])
1316 smc_tree_abort (errno);
1318 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1319 if (!entry || /* need create */
1320 entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
1321 entry->key != key) /* need insert */
1322 entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
1324 entry->value = value;
1325 g_mutex_unlock (&smc_tree_mutex);
1329 smc_tree_lookup (SmcKType key,
1332 SmcEntry *entry = NULL;
1333 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1334 gboolean found_one = FALSE;
1336 g_mutex_lock (&smc_tree_mutex);
1337 if (smc_tree_root && smc_tree_root[ix0])
1339 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1341 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1345 *value_p = entry->value;
1348 g_mutex_unlock (&smc_tree_mutex);
1353 smc_tree_remove (SmcKType key)
1355 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1356 gboolean found_one = FALSE;
1357 g_mutex_lock (&smc_tree_mutex);
1358 if (smc_tree_root && smc_tree_root[ix0])
1360 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1362 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1365 unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
1366 smc_tree_root[ix0][ix1].n_entries -= 1;
1367 g_memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
1368 if (!smc_tree_root[ix0][ix1].n_entries)
1370 /* avoid useless pressure on the memory system */
1371 free (smc_tree_root[ix0][ix1].entries);
1372 smc_tree_root[ix0][ix1].entries = NULL;
1377 g_mutex_unlock (&smc_tree_mutex);
1381 #ifdef G_ENABLE_DEBUG
1383 g_slice_debug_tree_statistics (void)
1385 g_mutex_lock (&smc_tree_mutex);
1388 unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
1390 for (i = 0; i < SMC_TRUNK_COUNT; i++)
1391 if (smc_tree_root[i])
1394 for (j = 0; j < SMC_BRANCH_COUNT; j++)
1395 if (smc_tree_root[i][j].n_entries)
1398 su += smc_tree_root[i][j].n_entries;
1399 en = MIN (en, smc_tree_root[i][j].n_entries);
1400 ex = MAX (ex, smc_tree_root[i][j].n_entries);
1402 else if (smc_tree_root[i][j].entries)
1403 o++; /* formerly used, now empty */
1406 tf = MAX (t, 1.0); /* max(1) to be a valid divisor */
1407 bf = MAX (b, 1.0); /* max(1) to be a valid divisor */
1408 fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
1409 fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1411 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
1412 fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1416 fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
1417 g_mutex_unlock (&smc_tree_mutex);
1419 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1420 * PID %CPU %MEM VSZ RSS COMMAND
1421 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1422 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1423 * 114017 103714 2354 344 0 108676 0
1424 * $ cat /proc/8887/status
1435 * (gdb) print g_slice_debug_tree_statistics ()
1436 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1437 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1438 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1441 #endif /* G_ENABLE_DEBUG */