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 2.1 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, see <http://www.gnu.org/licenses/>.
20 #include "glibconfig.h"
22 #if defined HAVE_POSIX_MEMALIGN && defined POSIX_MEMALIGN_WITH_COMPLIANT_ALLOCS
23 # define HAVE_COMPLIANT_POSIX_MEMALIGN 1
26 #if defined(HAVE_COMPLIANT_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE)
27 #define _XOPEN_SOURCE 600 /* posix_memalign() */
29 #include <stdlib.h> /* posix_memalign() */
34 #include <unistd.h> /* sysconf() */
41 #include <stdio.h> /* fputs */
46 #include "gmem.h" /* gslice.h */
47 #include "gstrfuncs.h"
49 #include "gtrashstack.h"
50 #include "gtestutils.h"
52 #include "glib_trace.h"
55 #include "gvalgrind.h"
58 * SECTION:memory_slices
59 * @title: Memory Slices
60 * @short_description: efficient way to allocate groups of equal-sized
63 * Memory slices provide a space-efficient and multi-processing scalable
64 * way to allocate equal-sized pieces of memory, just like the original
65 * #GMemChunks (from GLib 2.8), while avoiding their excessive
66 * memory-waste, scalability and performance problems.
68 * To achieve these goals, the slice allocator uses a sophisticated,
69 * layered design that has been inspired by Bonwick's slab allocator
70 * ([Bonwick94](http://citeseer.ist.psu.edu/bonwick94slab.html)
71 * Jeff Bonwick, The slab allocator: An object-caching kernel
72 * memory allocator. USENIX 1994, and
73 * [Bonwick01](http://citeseer.ist.psu.edu/bonwick01magazines.html)
74 * Bonwick and Jonathan Adams, Magazines and vmem: Extending the
75 * slab allocator to many cpu's and arbitrary resources. USENIX 2001)
77 * It uses posix_memalign() to optimize allocations of many equally-sized
78 * chunks, and has per-thread free lists (the so-called magazine layer)
79 * to quickly satisfy allocation requests of already known structure sizes.
80 * This is accompanied by extra caching logic to keep freed memory around
81 * for some time before returning it to the system. Memory that is unused
82 * due to alignment constraints is used for cache colorization (random
83 * distribution of chunk addresses) to improve CPU cache utilization. The
84 * caching layer of the slice allocator adapts itself to high lock contention
85 * to improve scalability.
87 * The slice allocator can allocate blocks as small as two pointers, and
88 * unlike malloc(), it does not reserve extra space per block. For large block
89 * sizes, g_slice_new() and g_slice_alloc() will automatically delegate to the
90 * system malloc() implementation. For newly written code it is recommended
91 * to use the new `g_slice` API instead of g_malloc() and
92 * friends, as long as objects are not resized during their lifetime and the
93 * object size used at allocation time is still available when freeing.
95 * Here is an example for using the slice allocator:
96 * |[<!-- language="C" -->
100 * // Allocate 10000 blocks.
101 * for (i = 0; i < 10000; i++)
103 * mem[i] = g_slice_alloc (50);
105 * // Fill in the memory with some junk.
106 * for (j = 0; j < 50; j++)
110 * // Now free all of the blocks.
111 * for (i = 0; i < 10000; i++)
112 * g_slice_free1 (50, mem[i]);
115 * And here is an example for using the using the slice allocator
116 * with data structures:
117 * |[<!-- language="C" -->
120 * // Allocate one block, using the g_slice_new() macro.
121 * array = g_slice_new (GRealArray);
123 * // We can now use array just like a normal pointer to a structure.
124 * array->data = NULL;
127 * array->zero_terminated = (zero_terminated ? 1 : 0);
128 * array->clear = (clear ? 1 : 0);
129 * array->elt_size = elt_size;
131 * // We can free the block, so it can be reused.
132 * g_slice_free (GRealArray, array);
136 /* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
137 * allocator and magazine extensions as outlined in:
138 * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
139 * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
140 * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
141 * slab allocator to many cpu's and arbitrary resources.
142 * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
144 * - the thread magazines. for each (aligned) chunk size, a magazine (a list)
145 * of recently freed and soon to be allocated chunks is maintained per thread.
146 * this way, most alloc/free requests can be quickly satisfied from per-thread
147 * free lists which only require one g_private_get() call to retrive the
149 * - the magazine cache. allocating and freeing chunks to/from threads only
150 * occours at magazine sizes from a global depot of magazines. the depot
151 * maintaines a 15 second working set of allocated magazines, so full
152 * magazines are not allocated and released too often.
153 * the chunk size dependent magazine sizes automatically adapt (within limits,
154 * see [3]) to lock contention to properly scale performance across a variety
156 * - the slab allocator. this allocator allocates slabs (blocks of memory) close
157 * to the system page size or multiples thereof which have to be page aligned.
158 * the blocks are divided into smaller chunks which are used to satisfy
159 * allocations from the upper layers. the space provided by the reminder of
160 * the chunk size division is used for cache colorization (random distribution
161 * of chunk addresses) to improve processor cache utilization. multiple slabs
162 * with the same chunk size are kept in a partially sorted ring to allow O(1)
163 * freeing and allocation of chunks (as long as the allocation of an entirely
164 * new slab can be avoided).
165 * - the page allocator. on most modern systems, posix_memalign(3) or
166 * memalign(3) should be available, so this is used to allocate blocks with
167 * system page size based alignments and sizes or multiples thereof.
168 * if no memalign variant is provided, valloc() is used instead and
169 * block sizes are limited to the system page size (no multiples thereof).
170 * as a fallback, on system without even valloc(), a malloc(3)-based page
171 * allocator with alloc-only behaviour is used.
174 * [1] some systems memalign(3) implementations may rely on boundary tagging for
175 * the handed out memory chunks. to avoid excessive page-wise fragmentation,
176 * we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
177 * specified in NATIVE_MALLOC_PADDING.
178 * [2] using the slab allocator alone already provides for a fast and efficient
179 * allocator, it doesn't properly scale beyond single-threaded uses though.
180 * also, the slab allocator implements eager free(3)-ing, i.e. does not
181 * provide any form of caching or working set maintenance. so if used alone,
182 * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
183 * at certain thresholds.
184 * [3] magazine sizes are bound by an implementation specific minimum size and
185 * a chunk size specific maximum to limit magazine storage sizes to roughly
187 * [4] allocating ca. 8 chunks per block/page keeps a good balance between
188 * external and internal fragmentation (<= 12.5%). [Bonwick94]
191 /* --- macros and constants --- */
192 #define LARGEALIGNMENT (256)
193 #define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
194 #define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
195 #define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
196 #define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
197 #define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
198 #define MIN_MAGAZINE_SIZE (4)
199 #define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
200 #define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
201 #define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
202 #define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
203 #define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
204 #define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
206 /* optimized version of ALIGN (size, P2ALIGNMENT) */
207 #if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
208 #define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
209 #elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
210 #define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
212 #define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
215 /* special helpers to avoid gmessage.c dependency */
216 static void mem_error (const char *format
, ...) G_GNUC_PRINTF (1,2);
217 #define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
219 /* --- structures --- */
220 typedef struct _ChunkLink ChunkLink
;
221 typedef struct _SlabInfo SlabInfo
;
222 typedef struct _CachedMagazine CachedMagazine
;
230 SlabInfo
*next
, *prev
;
234 gsize count
; /* approximative chunks list length */
237 Magazine
*magazine1
; /* array of MAX_SLAB_INDEX (allocator) */
238 Magazine
*magazine2
; /* array of MAX_SLAB_INDEX (allocator) */
241 gboolean always_malloc
;
242 gboolean bypass_magazines
;
243 gboolean debug_blocks
;
244 gsize working_set_msecs
;
245 guint color_increment
;
248 /* const after initialization */
249 gsize min_page_size
, max_page_size
;
251 gsize max_slab_chunk_size_for_magazine_cache
;
253 GMutex magazine_mutex
;
254 ChunkLink
**magazines
; /* array of MAX_SLAB_INDEX (allocator) */
255 guint
*contention_counters
; /* array of MAX_SLAB_INDEX (allocator) */
261 SlabInfo
**slab_stack
; /* array of MAX_SLAB_INDEX (allocator) */
265 /* --- g-slice prototypes --- */
266 static gpointer
slab_allocator_alloc_chunk (gsize chunk_size
);
267 static void slab_allocator_free_chunk (gsize chunk_size
,
269 static void private_thread_memory_cleanup (gpointer data
);
270 static gpointer
allocator_memalign (gsize alignment
,
272 static void allocator_memfree (gsize memsize
,
274 static inline void magazine_cache_update_stamp (void);
275 static inline gsize
allocator_get_magazine_threshold (Allocator
*allocator
,
278 /* --- g-slice memory checker --- */
279 static void smc_notify_alloc (void *pointer
,
281 static int smc_notify_free (void *pointer
,
284 /* --- variables --- */
285 static GPrivate private_thread_memory
= G_PRIVATE_INIT (private_thread_memory_cleanup
);
286 static gsize sys_page_size
= 0;
287 static Allocator allocator
[1] = { { 0, }, };
288 static SliceConfig slice_config
= {
289 FALSE
, /* always_malloc */
290 FALSE
, /* bypass_magazines */
291 FALSE
, /* debug_blocks */
292 15 * 1000, /* working_set_msecs */
293 1, /* color increment, alt: 0x7fffffff */
295 static GMutex smc_tree_mutex
; /* mutex for G_SLICE=debug-blocks */
297 /* --- auxiliary funcitons --- */
299 g_slice_set_config (GSliceConfig ckey
,
302 g_return_if_fail (sys_page_size
== 0);
305 case G_SLICE_CONFIG_ALWAYS_MALLOC
:
306 slice_config
.always_malloc
= value
!= 0;
308 case G_SLICE_CONFIG_BYPASS_MAGAZINES
:
309 slice_config
.bypass_magazines
= value
!= 0;
311 case G_SLICE_CONFIG_WORKING_SET_MSECS
:
312 slice_config
.working_set_msecs
= value
;
314 case G_SLICE_CONFIG_COLOR_INCREMENT
:
315 slice_config
.color_increment
= value
;
321 g_slice_get_config (GSliceConfig ckey
)
325 case G_SLICE_CONFIG_ALWAYS_MALLOC
:
326 return slice_config
.always_malloc
;
327 case G_SLICE_CONFIG_BYPASS_MAGAZINES
:
328 return slice_config
.bypass_magazines
;
329 case G_SLICE_CONFIG_WORKING_SET_MSECS
:
330 return slice_config
.working_set_msecs
;
331 case G_SLICE_CONFIG_CHUNK_SIZES
:
332 return MAX_SLAB_INDEX (allocator
);
333 case G_SLICE_CONFIG_COLOR_INCREMENT
:
334 return slice_config
.color_increment
;
341 g_slice_get_config_state (GSliceConfig ckey
,
346 g_return_val_if_fail (n_values
!= NULL
, NULL
);
351 case G_SLICE_CONFIG_CONTENTION_COUNTER
:
352 array
[i
++] = SLAB_CHUNK_SIZE (allocator
, address
);
353 array
[i
++] = allocator
->contention_counters
[address
];
354 array
[i
++] = allocator_get_magazine_threshold (allocator
, address
);
356 return g_memdup (array
, sizeof (array
[0]) * *n_values
);
363 slice_config_init (SliceConfig
*config
)
367 *config
= slice_config
;
369 val
= getenv ("G_SLICE");
373 const GDebugKey keys
[] = {
374 { "always-malloc", 1 << 0 },
375 { "debug-blocks", 1 << 1 },
378 flags
= g_parse_debug_string (val
, keys
, G_N_ELEMENTS (keys
));
379 if (flags
& (1 << 0))
380 config
->always_malloc
= TRUE
;
381 if (flags
& (1 << 1))
382 config
->debug_blocks
= TRUE
;
386 /* G_SLICE was not specified, so check if valgrind is running and
387 * disable ourselves if it is.
389 * This way it's possible to force gslice to be enabled under
390 * valgrind just by setting G_SLICE to the empty string.
392 #ifdef ENABLE_VALGRIND
393 if (RUNNING_ON_VALGRIND
)
394 config
->always_malloc
= TRUE
;
400 g_slice_init_nomessage (void)
402 /* we may not use g_error() or friends here */
403 mem_assert (sys_page_size
== 0);
404 mem_assert (MIN_MAGAZINE_SIZE
>= 4);
408 SYSTEM_INFO system_info
;
409 GetSystemInfo (&system_info
);
410 sys_page_size
= system_info
.dwPageSize
;
413 sys_page_size
= sysconf (_SC_PAGESIZE
); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */
415 mem_assert (sys_page_size
>= 2 * LARGEALIGNMENT
);
416 mem_assert ((sys_page_size
& (sys_page_size
- 1)) == 0);
417 slice_config_init (&allocator
->config
);
418 allocator
->min_page_size
= sys_page_size
;
419 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN
420 /* allow allocation of pages up to 8KB (with 8KB alignment).
421 * this is useful because many medium to large sized structures
422 * fit less than 8 times (see [4]) into 4KB pages.
423 * we allow very small page sizes here, to reduce wastage in
424 * threads if only small allocations are required (this does
425 * bear the risk of increasing allocation times and fragmentation
428 allocator
->min_page_size
= MAX (allocator
->min_page_size
, 4096);
429 allocator
->max_page_size
= MAX (allocator
->min_page_size
, 8192);
430 allocator
->min_page_size
= MIN (allocator
->min_page_size
, 128);
432 /* we can only align to system page size */
433 allocator
->max_page_size
= sys_page_size
;
435 if (allocator
->config
.always_malloc
)
437 allocator
->contention_counters
= NULL
;
438 allocator
->magazines
= NULL
;
439 allocator
->slab_stack
= NULL
;
443 allocator
->contention_counters
= g_new0 (guint
, MAX_SLAB_INDEX (allocator
));
444 allocator
->magazines
= g_new0 (ChunkLink
*, MAX_SLAB_INDEX (allocator
));
445 allocator
->slab_stack
= g_new0 (SlabInfo
*, MAX_SLAB_INDEX (allocator
));
448 allocator
->mutex_counter
= 0;
449 allocator
->stamp_counter
= MAX_STAMP_COUNTER
; /* force initial update */
450 allocator
->last_stamp
= 0;
451 allocator
->color_accu
= 0;
452 magazine_cache_update_stamp();
453 /* values cached for performance reasons */
454 allocator
->max_slab_chunk_size_for_magazine_cache
= MAX_SLAB_CHUNK_SIZE (allocator
);
455 if (allocator
->config
.always_malloc
|| allocator
->config
.bypass_magazines
)
456 allocator
->max_slab_chunk_size_for_magazine_cache
= 0; /* non-optimized cases */
460 allocator_categorize (gsize aligned_chunk_size
)
462 /* speed up the likely path */
463 if (G_LIKELY (aligned_chunk_size
&& aligned_chunk_size
<= allocator
->max_slab_chunk_size_for_magazine_cache
))
464 return 1; /* use magazine cache */
466 if (!allocator
->config
.always_malloc
&&
467 aligned_chunk_size
&&
468 aligned_chunk_size
<= MAX_SLAB_CHUNK_SIZE (allocator
))
470 if (allocator
->config
.bypass_magazines
)
471 return 2; /* use slab allocator, see [2] */
472 return 1; /* use magazine cache */
474 return 0; /* use malloc() */
478 g_mutex_lock_a (GMutex
*mutex
,
479 guint
*contention_counter
)
481 gboolean contention
= FALSE
;
482 if (!g_mutex_trylock (mutex
))
484 g_mutex_lock (mutex
);
489 allocator
->mutex_counter
++;
490 if (allocator
->mutex_counter
>= 1) /* quickly adapt to contention */
492 allocator
->mutex_counter
= 0;
493 *contention_counter
= MIN (*contention_counter
+ 1, MAX_MAGAZINE_SIZE
);
496 else /* !contention */
498 allocator
->mutex_counter
--;
499 if (allocator
->mutex_counter
< -11) /* moderately recover magazine sizes */
501 allocator
->mutex_counter
= 0;
502 *contention_counter
= MAX (*contention_counter
, 1) - 1;
507 static inline ThreadMemory
*
508 thread_memory_from_self (void)
510 ThreadMemory
*tmem
= g_private_get (&private_thread_memory
);
511 if (G_UNLIKELY (!tmem
))
513 static GMutex init_mutex
;
516 g_mutex_lock (&init_mutex
);
517 if G_UNLIKELY (sys_page_size
== 0)
518 g_slice_init_nomessage ();
519 g_mutex_unlock (&init_mutex
);
521 n_magazines
= MAX_SLAB_INDEX (allocator
);
522 tmem
= g_malloc0 (sizeof (ThreadMemory
) + sizeof (Magazine
) * 2 * n_magazines
);
523 tmem
->magazine1
= (Magazine
*) (tmem
+ 1);
524 tmem
->magazine2
= &tmem
->magazine1
[n_magazines
];
525 g_private_set (&private_thread_memory
, tmem
);
530 static inline ChunkLink
*
531 magazine_chain_pop_head (ChunkLink
**magazine_chunks
)
533 /* magazine chains are linked via ChunkLink->next.
534 * each ChunkLink->data of the toplevel chain may point to a subchain,
535 * linked via ChunkLink->next. ChunkLink->data of the subchains just
536 * contains uninitialized junk.
538 ChunkLink
*chunk
= (*magazine_chunks
)->data
;
539 if (G_UNLIKELY (chunk
))
541 /* allocating from freed list */
542 (*magazine_chunks
)->data
= chunk
->next
;
546 chunk
= *magazine_chunks
;
547 *magazine_chunks
= chunk
->next
;
552 #if 0 /* useful for debugging */
554 magazine_count (ChunkLink
*head
)
561 ChunkLink
*child
= head
->data
;
563 for (child
= head
->data
; child
; child
= child
->next
)
572 allocator_get_magazine_threshold (Allocator
*allocator
,
575 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
576 * which is required by the implementation. also, for moderately sized chunks
577 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
578 * of chunks available per page/2 to avoid excessive traffic in the magazine
579 * cache for small to medium sized structures.
580 * the upper bound of the magazine size is effectively provided by
581 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
582 * the content of a single magazine doesn't exceed ca. 16KB.
584 gsize chunk_size
= SLAB_CHUNK_SIZE (allocator
, ix
);
585 guint threshold
= MAX (MIN_MAGAZINE_SIZE
, allocator
->max_page_size
/ MAX (5 * chunk_size
, 5 * 32));
586 guint contention_counter
= allocator
->contention_counters
[ix
];
587 if (G_UNLIKELY (contention_counter
)) /* single CPU bias */
589 /* adapt contention counter thresholds to chunk sizes */
590 contention_counter
= contention_counter
* 64 / chunk_size
;
591 threshold
= MAX (threshold
, contention_counter
);
596 /* --- magazine cache --- */
598 magazine_cache_update_stamp (void)
600 if (allocator
->stamp_counter
>= MAX_STAMP_COUNTER
)
603 g_get_current_time (&tv
);
604 allocator
->last_stamp
= tv
.tv_sec
* 1000 + tv
.tv_usec
/ 1000; /* milli seconds */
605 allocator
->stamp_counter
= 0;
608 allocator
->stamp_counter
++;
611 static inline ChunkLink
*
612 magazine_chain_prepare_fields (ChunkLink
*magazine_chunks
)
618 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
619 /* ensure a magazine with at least 4 unused data pointers */
620 chunk1
= magazine_chain_pop_head (&magazine_chunks
);
621 chunk2
= magazine_chain_pop_head (&magazine_chunks
);
622 chunk3
= magazine_chain_pop_head (&magazine_chunks
);
623 chunk4
= magazine_chain_pop_head (&magazine_chunks
);
624 chunk4
->next
= magazine_chunks
;
625 chunk3
->next
= chunk4
;
626 chunk2
->next
= chunk3
;
627 chunk1
->next
= chunk2
;
631 /* access the first 3 fields of a specially prepared magazine chain */
632 #define magazine_chain_prev(mc) ((mc)->data)
633 #define magazine_chain_stamp(mc) ((mc)->next->data)
634 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
635 #define magazine_chain_next(mc) ((mc)->next->next->data)
636 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
639 magazine_cache_trim (Allocator
*allocator
,
643 /* g_mutex_lock (allocator->mutex); done by caller */
644 /* trim magazine cache from tail */
645 ChunkLink
*current
= magazine_chain_prev (allocator
->magazines
[ix
]);
646 ChunkLink
*trash
= NULL
;
647 while (ABS (stamp
- magazine_chain_uint_stamp (current
)) >= allocator
->config
.working_set_msecs
)
650 ChunkLink
*prev
= magazine_chain_prev (current
);
651 ChunkLink
*next
= magazine_chain_next (current
);
652 magazine_chain_next (prev
) = next
;
653 magazine_chain_prev (next
) = prev
;
654 /* clear special fields, put on trash stack */
655 magazine_chain_next (current
) = NULL
;
656 magazine_chain_count (current
) = NULL
;
657 magazine_chain_stamp (current
) = NULL
;
658 magazine_chain_prev (current
) = trash
;
660 /* fixup list head if required */
661 if (current
== allocator
->magazines
[ix
])
663 allocator
->magazines
[ix
] = NULL
;
668 g_mutex_unlock (&allocator
->magazine_mutex
);
672 const gsize chunk_size
= SLAB_CHUNK_SIZE (allocator
, ix
);
673 g_mutex_lock (&allocator
->slab_mutex
);
677 trash
= magazine_chain_prev (current
);
678 magazine_chain_prev (current
) = NULL
; /* clear special field */
681 ChunkLink
*chunk
= magazine_chain_pop_head (¤t
);
682 slab_allocator_free_chunk (chunk_size
, chunk
);
685 g_mutex_unlock (&allocator
->slab_mutex
);
690 magazine_cache_push_magazine (guint ix
,
691 ChunkLink
*magazine_chunks
,
692 gsize count
) /* must be >= MIN_MAGAZINE_SIZE */
694 ChunkLink
*current
= magazine_chain_prepare_fields (magazine_chunks
);
695 ChunkLink
*next
, *prev
;
696 g_mutex_lock (&allocator
->magazine_mutex
);
697 /* add magazine at head */
698 next
= allocator
->magazines
[ix
];
700 prev
= magazine_chain_prev (next
);
702 next
= prev
= current
;
703 magazine_chain_next (prev
) = current
;
704 magazine_chain_prev (next
) = current
;
705 magazine_chain_prev (current
) = prev
;
706 magazine_chain_next (current
) = next
;
707 magazine_chain_count (current
) = (gpointer
) count
;
709 magazine_cache_update_stamp();
710 magazine_chain_stamp (current
) = GUINT_TO_POINTER (allocator
->last_stamp
);
711 allocator
->magazines
[ix
] = current
;
712 /* free old magazines beyond a certain threshold */
713 magazine_cache_trim (allocator
, ix
, allocator
->last_stamp
);
714 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
718 magazine_cache_pop_magazine (guint ix
,
721 g_mutex_lock_a (&allocator
->magazine_mutex
, &allocator
->contention_counters
[ix
]);
722 if (!allocator
->magazines
[ix
])
724 guint magazine_threshold
= allocator_get_magazine_threshold (allocator
, ix
);
725 gsize i
, chunk_size
= SLAB_CHUNK_SIZE (allocator
, ix
);
726 ChunkLink
*chunk
, *head
;
727 g_mutex_unlock (&allocator
->magazine_mutex
);
728 g_mutex_lock (&allocator
->slab_mutex
);
729 head
= slab_allocator_alloc_chunk (chunk_size
);
732 for (i
= 1; i
< magazine_threshold
; i
++)
734 chunk
->next
= slab_allocator_alloc_chunk (chunk_size
);
739 g_mutex_unlock (&allocator
->slab_mutex
);
745 ChunkLink
*current
= allocator
->magazines
[ix
];
746 ChunkLink
*prev
= magazine_chain_prev (current
);
747 ChunkLink
*next
= magazine_chain_next (current
);
749 magazine_chain_next (prev
) = next
;
750 magazine_chain_prev (next
) = prev
;
751 allocator
->magazines
[ix
] = next
== current
? NULL
: next
;
752 g_mutex_unlock (&allocator
->magazine_mutex
);
753 /* clear special fields and hand out */
754 *countp
= (gsize
) magazine_chain_count (current
);
755 magazine_chain_prev (current
) = NULL
;
756 magazine_chain_next (current
) = NULL
;
757 magazine_chain_count (current
) = NULL
;
758 magazine_chain_stamp (current
) = NULL
;
763 /* --- thread magazines --- */
765 private_thread_memory_cleanup (gpointer data
)
767 ThreadMemory
*tmem
= data
;
768 const guint n_magazines
= MAX_SLAB_INDEX (allocator
);
770 for (ix
= 0; ix
< n_magazines
; ix
++)
774 mags
[0] = &tmem
->magazine1
[ix
];
775 mags
[1] = &tmem
->magazine2
[ix
];
776 for (j
= 0; j
< 2; j
++)
778 Magazine
*mag
= mags
[j
];
779 if (mag
->count
>= MIN_MAGAZINE_SIZE
)
780 magazine_cache_push_magazine (ix
, mag
->chunks
, mag
->count
);
783 const gsize chunk_size
= SLAB_CHUNK_SIZE (allocator
, ix
);
784 g_mutex_lock (&allocator
->slab_mutex
);
787 ChunkLink
*chunk
= magazine_chain_pop_head (&mag
->chunks
);
788 slab_allocator_free_chunk (chunk_size
, chunk
);
790 g_mutex_unlock (&allocator
->slab_mutex
);
798 thread_memory_magazine1_reload (ThreadMemory
*tmem
,
801 Magazine
*mag
= &tmem
->magazine1
[ix
];
802 mem_assert (mag
->chunks
== NULL
); /* ensure that we may reset mag->count */
804 mag
->chunks
= magazine_cache_pop_magazine (ix
, &mag
->count
);
808 thread_memory_magazine2_unload (ThreadMemory
*tmem
,
811 Magazine
*mag
= &tmem
->magazine2
[ix
];
812 magazine_cache_push_magazine (ix
, mag
->chunks
, mag
->count
);
818 thread_memory_swap_magazines (ThreadMemory
*tmem
,
821 Magazine xmag
= tmem
->magazine1
[ix
];
822 tmem
->magazine1
[ix
] = tmem
->magazine2
[ix
];
823 tmem
->magazine2
[ix
] = xmag
;
826 static inline gboolean
827 thread_memory_magazine1_is_empty (ThreadMemory
*tmem
,
830 return tmem
->magazine1
[ix
].chunks
== NULL
;
833 static inline gboolean
834 thread_memory_magazine2_is_full (ThreadMemory
*tmem
,
837 return tmem
->magazine2
[ix
].count
>= allocator_get_magazine_threshold (allocator
, ix
);
840 static inline gpointer
841 thread_memory_magazine1_alloc (ThreadMemory
*tmem
,
844 Magazine
*mag
= &tmem
->magazine1
[ix
];
845 ChunkLink
*chunk
= magazine_chain_pop_head (&mag
->chunks
);
846 if (G_LIKELY (mag
->count
> 0))
852 thread_memory_magazine2_free (ThreadMemory
*tmem
,
856 Magazine
*mag
= &tmem
->magazine2
[ix
];
857 ChunkLink
*chunk
= mem
;
859 chunk
->next
= mag
->chunks
;
864 /* --- API functions --- */
868 * @type: the type to allocate, typically a structure name
870 * A convenience macro to allocate a block of memory from the
873 * It calls g_slice_alloc() with `sizeof (@type)` and casts the
874 * returned pointer to a pointer of the given type, avoiding a type
875 * cast in the source code. Note that the underlying slice allocation
876 * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
877 * environment variable.
879 * This can never return %NULL as the minimum allocation size from
880 * `sizeof (@type)` is 1 byte.
882 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
890 * @type: the type to allocate, typically a structure name
892 * A convenience macro to allocate a block of memory from the
893 * slice allocator and set the memory to 0.
895 * It calls g_slice_alloc0() with `sizeof (@type)`
896 * and casts the returned pointer to a pointer of the given type,
897 * avoiding a type cast in the source code.
898 * Note that the underlying slice allocation mechanism can
899 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
900 * environment variable.
902 * This can never return %NULL as the minimum allocation size from
903 * `sizeof (@type)` is 1 byte.
905 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
913 * @type: the type to duplicate, typically a structure name
914 * @mem: (not nullable): the memory to copy into the allocated block
916 * A convenience macro to duplicate a block of memory using
917 * the slice allocator.
919 * It calls g_slice_copy() with `sizeof (@type)`
920 * and casts the returned pointer to a pointer of the given type,
921 * avoiding a type cast in the source code.
922 * Note that the underlying slice allocation mechanism can
923 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
924 * environment variable.
926 * This can never return %NULL.
928 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
936 * @type: the type of the block to free, typically a structure name
937 * @mem: a pointer to the block to free
939 * A convenience macro to free a block of memory that has
940 * been allocated from the slice allocator.
942 * It calls g_slice_free1() using `sizeof (type)`
944 * Note that the exact release behaviour can be changed with the
945 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
946 * [`G_SLICE`][G_SLICE] for related debugging options.
948 * If @mem is %NULL, this macro does nothing.
954 * g_slice_free_chain:
955 * @type: the type of the @mem_chain blocks
956 * @mem_chain: a pointer to the first block of the chain
957 * @next: the field name of the next pointer in @type
959 * Frees a linked list of memory blocks of structure type @type.
960 * The memory blocks must be equal-sized, allocated via
961 * g_slice_alloc() or g_slice_alloc0() and linked together by
962 * a @next pointer (similar to #GSList). The name of the
963 * @next field in @type is passed as third argument.
964 * Note that the exact release behaviour can be changed with the
965 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
966 * [`G_SLICE`][G_SLICE] for related debugging options.
968 * If @mem_chain is %NULL, this function does nothing.
975 * @block_size: the number of bytes to allocate
977 * Allocates a block of memory from the slice allocator.
978 * The block address handed out can be expected to be aligned
979 * to at least 1 * sizeof (void*),
980 * though in general slices are 2 * sizeof (void*) bytes aligned,
981 * if a malloc() fallback implementation is used instead,
982 * the alignment may be reduced in a libc dependent fashion.
983 * Note that the underlying slice allocation mechanism can
984 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
985 * environment variable.
987 * Returns: a pointer to the allocated memory block, which will be %NULL if and
988 * only if @mem_size is 0
993 g_slice_alloc (gsize mem_size
)
1000 /* This gets the private structure for this thread. If the private
1001 * structure does not yet exist, it is created.
1003 * This has a side effect of causing GSlice to be initialised, so it
1006 tmem
= thread_memory_from_self ();
1008 chunk_size
= P2ALIGN (mem_size
);
1009 acat
= allocator_categorize (chunk_size
);
1010 if (G_LIKELY (acat
== 1)) /* allocate through magazine layer */
1012 guint ix
= SLAB_INDEX (allocator
, chunk_size
);
1013 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem
, ix
)))
1015 thread_memory_swap_magazines (tmem
, ix
);
1016 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem
, ix
)))
1017 thread_memory_magazine1_reload (tmem
, ix
);
1019 mem
= thread_memory_magazine1_alloc (tmem
, ix
);
1021 else if (acat
== 2) /* allocate through slab allocator */
1023 g_mutex_lock (&allocator
->slab_mutex
);
1024 mem
= slab_allocator_alloc_chunk (chunk_size
);
1025 g_mutex_unlock (&allocator
->slab_mutex
);
1027 else /* delegate to system malloc */
1028 mem
= g_malloc (mem_size
);
1029 if (G_UNLIKELY (allocator
->config
.debug_blocks
))
1030 smc_notify_alloc (mem
, mem_size
);
1032 TRACE (GLIB_SLICE_ALLOC((void*)mem
, mem_size
));
1039 * @block_size: the number of bytes to allocate
1041 * Allocates a block of memory via g_slice_alloc() and initializes
1042 * the returned memory to 0. Note that the underlying slice allocation
1043 * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
1044 * environment variable.
1046 * Returns: a pointer to the allocated block, which will be %NULL if and only
1052 g_slice_alloc0 (gsize mem_size
)
1054 gpointer mem
= g_slice_alloc (mem_size
);
1056 memset (mem
, 0, mem_size
);
1062 * @block_size: the number of bytes to allocate
1063 * @mem_block: the memory to copy
1065 * Allocates a block of memory from the slice allocator
1066 * and copies @block_size bytes into it from @mem_block.
1068 * @mem_block must be non-%NULL if @block_size is non-zero.
1070 * Returns: a pointer to the allocated memory block, which will be %NULL if and
1071 * only if @mem_size is 0
1076 g_slice_copy (gsize mem_size
,
1077 gconstpointer mem_block
)
1079 gpointer mem
= g_slice_alloc (mem_size
);
1081 memcpy (mem
, mem_block
, mem_size
);
1087 * @block_size: the size of the block
1088 * @mem_block: a pointer to the block to free
1090 * Frees a block of memory.
1092 * The memory must have been allocated via g_slice_alloc() or
1093 * g_slice_alloc0() and the @block_size has to match the size
1094 * specified upon allocation. Note that the exact release behaviour
1095 * can be changed with the [`G_DEBUG=gc-friendly`][G_DEBUG] environment
1096 * variable, also see [`G_SLICE`][G_SLICE] for related debugging options.
1098 * If @mem_block is %NULL, this function does nothing.
1103 g_slice_free1 (gsize mem_size
,
1106 gsize chunk_size
= P2ALIGN (mem_size
);
1107 guint acat
= allocator_categorize (chunk_size
);
1108 if (G_UNLIKELY (!mem_block
))
1110 if (G_UNLIKELY (allocator
->config
.debug_blocks
) &&
1111 !smc_notify_free (mem_block
, mem_size
))
1113 if (G_LIKELY (acat
== 1)) /* allocate through magazine layer */
1115 ThreadMemory
*tmem
= thread_memory_from_self();
1116 guint ix
= SLAB_INDEX (allocator
, chunk_size
);
1117 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem
, ix
)))
1119 thread_memory_swap_magazines (tmem
, ix
);
1120 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem
, ix
)))
1121 thread_memory_magazine2_unload (tmem
, ix
);
1123 if (G_UNLIKELY (g_mem_gc_friendly
))
1124 memset (mem_block
, 0, chunk_size
);
1125 thread_memory_magazine2_free (tmem
, ix
, mem_block
);
1127 else if (acat
== 2) /* allocate through slab allocator */
1129 if (G_UNLIKELY (g_mem_gc_friendly
))
1130 memset (mem_block
, 0, chunk_size
);
1131 g_mutex_lock (&allocator
->slab_mutex
);
1132 slab_allocator_free_chunk (chunk_size
, mem_block
);
1133 g_mutex_unlock (&allocator
->slab_mutex
);
1135 else /* delegate to system malloc */
1137 if (G_UNLIKELY (g_mem_gc_friendly
))
1138 memset (mem_block
, 0, mem_size
);
1141 TRACE (GLIB_SLICE_FREE((void*)mem_block
, mem_size
));
1145 * g_slice_free_chain_with_offset:
1146 * @block_size: the size of the blocks
1147 * @mem_chain: a pointer to the first block of the chain
1148 * @next_offset: the offset of the @next field in the blocks
1150 * Frees a linked list of memory blocks of structure type @type.
1152 * The memory blocks must be equal-sized, allocated via
1153 * g_slice_alloc() or g_slice_alloc0() and linked together by a
1154 * @next pointer (similar to #GSList). The offset of the @next
1155 * field in each block is passed as third argument.
1156 * Note that the exact release behaviour can be changed with the
1157 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
1158 * [`G_SLICE`][G_SLICE] for related debugging options.
1160 * If @mem_chain is %NULL, this function does nothing.
1165 g_slice_free_chain_with_offset (gsize mem_size
,
1169 gpointer slice
= mem_chain
;
1170 /* while the thread magazines and the magazine cache are implemented so that
1171 * they can easily be extended to allow for free lists containing more free
1172 * lists for the first level nodes, which would allow O(1) freeing in this
1173 * function, the benefit of such an extension is questionable, because:
1174 * - the magazine size counts will become mere lower bounds which confuses
1175 * the code adapting to lock contention;
1176 * - freeing a single node to the thread magazines is very fast, so this
1177 * O(list_length) operation is multiplied by a fairly small factor;
1178 * - memory usage histograms on larger applications seem to indicate that
1179 * the amount of released multi node lists is negligible in comparison
1180 * to single node releases.
1181 * - the major performance bottle neck, namely g_private_get() or
1182 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
1183 * inner loop for freeing chained slices.
1185 gsize chunk_size
= P2ALIGN (mem_size
);
1186 guint acat
= allocator_categorize (chunk_size
);
1187 if (G_LIKELY (acat
== 1)) /* allocate through magazine layer */
1189 ThreadMemory
*tmem
= thread_memory_from_self();
1190 guint ix
= SLAB_INDEX (allocator
, chunk_size
);
1193 guint8
*current
= slice
;
1194 slice
= *(gpointer
*) (current
+ next_offset
);
1195 if (G_UNLIKELY (allocator
->config
.debug_blocks
) &&
1196 !smc_notify_free (current
, mem_size
))
1198 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem
, ix
)))
1200 thread_memory_swap_magazines (tmem
, ix
);
1201 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem
, ix
)))
1202 thread_memory_magazine2_unload (tmem
, ix
);
1204 if (G_UNLIKELY (g_mem_gc_friendly
))
1205 memset (current
, 0, chunk_size
);
1206 thread_memory_magazine2_free (tmem
, ix
, current
);
1209 else if (acat
== 2) /* allocate through slab allocator */
1211 g_mutex_lock (&allocator
->slab_mutex
);
1214 guint8
*current
= slice
;
1215 slice
= *(gpointer
*) (current
+ next_offset
);
1216 if (G_UNLIKELY (allocator
->config
.debug_blocks
) &&
1217 !smc_notify_free (current
, mem_size
))
1219 if (G_UNLIKELY (g_mem_gc_friendly
))
1220 memset (current
, 0, chunk_size
);
1221 slab_allocator_free_chunk (chunk_size
, current
);
1223 g_mutex_unlock (&allocator
->slab_mutex
);
1225 else /* delegate to system malloc */
1228 guint8
*current
= slice
;
1229 slice
= *(gpointer
*) (current
+ next_offset
);
1230 if (G_UNLIKELY (allocator
->config
.debug_blocks
) &&
1231 !smc_notify_free (current
, mem_size
))
1233 if (G_UNLIKELY (g_mem_gc_friendly
))
1234 memset (current
, 0, mem_size
);
1239 /* --- single page allocator --- */
1241 allocator_slab_stack_push (Allocator
*allocator
,
1245 /* insert slab at slab ring head */
1246 if (!allocator
->slab_stack
[ix
])
1248 sinfo
->next
= sinfo
;
1249 sinfo
->prev
= sinfo
;
1253 SlabInfo
*next
= allocator
->slab_stack
[ix
], *prev
= next
->prev
;
1259 allocator
->slab_stack
[ix
] = sinfo
;
1263 allocator_aligned_page_size (Allocator
*allocator
,
1266 gsize val
= 1 << g_bit_storage (n_bytes
- 1);
1267 val
= MAX (val
, allocator
->min_page_size
);
1272 allocator_add_slab (Allocator
*allocator
,
1278 gsize addr
, padding
, n_chunks
, color
= 0;
1281 gpointer aligned_memory
;
1285 page_size
= allocator_aligned_page_size (allocator
, SLAB_BPAGE_SIZE (allocator
, chunk_size
));
1286 /* allocate 1 page for the chunks and the slab */
1287 aligned_memory
= allocator_memalign (page_size
, page_size
- NATIVE_MALLOC_PADDING
);
1289 mem
= aligned_memory
;
1293 const gchar
*syserr
= strerror (errsv
);
1294 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
1295 (guint
) (page_size
- NATIVE_MALLOC_PADDING
), (guint
) page_size
, syserr
);
1297 /* mask page address */
1298 addr
= ((gsize
) mem
/ page_size
) * page_size
;
1299 /* assert alignment */
1300 mem_assert (aligned_memory
== (gpointer
) addr
);
1301 /* basic slab info setup */
1302 sinfo
= (SlabInfo
*) (mem
+ page_size
- SLAB_INFO_SIZE
);
1303 sinfo
->n_allocated
= 0;
1304 sinfo
->chunks
= NULL
;
1305 /* figure cache colorization */
1306 n_chunks
= ((guint8
*) sinfo
- mem
) / chunk_size
;
1307 padding
= ((guint8
*) sinfo
- mem
) - n_chunks
* chunk_size
;
1310 color
= (allocator
->color_accu
* P2ALIGNMENT
) % padding
;
1311 allocator
->color_accu
+= allocator
->config
.color_increment
;
1313 /* add chunks to free list */
1314 chunk
= (ChunkLink
*) (mem
+ color
);
1315 sinfo
->chunks
= chunk
;
1316 for (i
= 0; i
< n_chunks
- 1; i
++)
1318 chunk
->next
= (ChunkLink
*) ((guint8
*) chunk
+ chunk_size
);
1319 chunk
= chunk
->next
;
1321 chunk
->next
= NULL
; /* last chunk */
1322 /* add slab to slab ring */
1323 allocator_slab_stack_push (allocator
, ix
, sinfo
);
1327 slab_allocator_alloc_chunk (gsize chunk_size
)
1330 guint ix
= SLAB_INDEX (allocator
, chunk_size
);
1331 /* ensure non-empty slab */
1332 if (!allocator
->slab_stack
[ix
] || !allocator
->slab_stack
[ix
]->chunks
)
1333 allocator_add_slab (allocator
, ix
, chunk_size
);
1334 /* allocate chunk */
1335 chunk
= allocator
->slab_stack
[ix
]->chunks
;
1336 allocator
->slab_stack
[ix
]->chunks
= chunk
->next
;
1337 allocator
->slab_stack
[ix
]->n_allocated
++;
1338 /* rotate empty slabs */
1339 if (!allocator
->slab_stack
[ix
]->chunks
)
1340 allocator
->slab_stack
[ix
] = allocator
->slab_stack
[ix
]->next
;
1345 slab_allocator_free_chunk (gsize chunk_size
,
1350 guint ix
= SLAB_INDEX (allocator
, chunk_size
);
1351 gsize page_size
= allocator_aligned_page_size (allocator
, SLAB_BPAGE_SIZE (allocator
, chunk_size
));
1352 gsize addr
= ((gsize
) mem
/ page_size
) * page_size
;
1353 /* mask page address */
1354 guint8
*page
= (guint8
*) addr
;
1355 SlabInfo
*sinfo
= (SlabInfo
*) (page
+ page_size
- SLAB_INFO_SIZE
);
1356 /* assert valid chunk count */
1357 mem_assert (sinfo
->n_allocated
> 0);
1358 /* add chunk to free list */
1359 was_empty
= sinfo
->chunks
== NULL
;
1360 chunk
= (ChunkLink
*) mem
;
1361 chunk
->next
= sinfo
->chunks
;
1362 sinfo
->chunks
= chunk
;
1363 sinfo
->n_allocated
--;
1364 /* keep slab ring partially sorted, empty slabs at end */
1368 SlabInfo
*next
= sinfo
->next
, *prev
= sinfo
->prev
;
1371 if (allocator
->slab_stack
[ix
] == sinfo
)
1372 allocator
->slab_stack
[ix
] = next
== sinfo
? NULL
: next
;
1373 /* insert slab at head */
1374 allocator_slab_stack_push (allocator
, ix
, sinfo
);
1376 /* eagerly free complete unused slabs */
1377 if (!sinfo
->n_allocated
)
1380 SlabInfo
*next
= sinfo
->next
, *prev
= sinfo
->prev
;
1383 if (allocator
->slab_stack
[ix
] == sinfo
)
1384 allocator
->slab_stack
[ix
] = next
== sinfo
? NULL
: next
;
1386 allocator_memfree (page_size
, page
);
1390 /* --- memalign implementation --- */
1391 #ifdef HAVE_MALLOC_H
1392 #include <malloc.h> /* memalign() */
1396 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1397 * define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
1398 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1399 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1400 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1403 #if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1404 static GTrashStack
*compat_valloc_trash
= NULL
;
1408 allocator_memalign (gsize alignment
,
1411 gpointer aligned_memory
= NULL
;
1413 #if HAVE_COMPLIANT_POSIX_MEMALIGN
1414 err
= posix_memalign (&aligned_memory
, alignment
, memsize
);
1417 aligned_memory
= memalign (alignment
, memsize
);
1421 aligned_memory
= valloc (memsize
);
1424 /* simplistic non-freeing page allocator */
1425 mem_assert (alignment
== sys_page_size
);
1426 mem_assert (memsize
<= sys_page_size
);
1427 if (!compat_valloc_trash
)
1429 const guint n_pages
= 16;
1430 guint8
*mem
= malloc (n_pages
* sys_page_size
);
1435 guint8
*amem
= (guint8
*) ALIGN ((gsize
) mem
, sys_page_size
);
1437 i
--; /* mem wasn't page aligned */
1438 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1440 g_trash_stack_push (&compat_valloc_trash
, amem
+ i
* sys_page_size
);
1441 G_GNUC_END_IGNORE_DEPRECATIONS
1444 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1445 aligned_memory
= g_trash_stack_pop (&compat_valloc_trash
);
1446 G_GNUC_END_IGNORE_DEPRECATIONS
1448 if (!aligned_memory
)
1450 return aligned_memory
;
1454 allocator_memfree (gsize memsize
,
1457 #if HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1460 mem_assert (memsize
<= sys_page_size
);
1461 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1462 g_trash_stack_push (&compat_valloc_trash
, mem
);
1463 G_GNUC_END_IGNORE_DEPRECATIONS
1468 mem_error (const char *format
,
1473 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1474 fputs ("\n***MEMORY-ERROR***: ", stderr
);
1475 pname
= g_get_prgname();
1476 g_fprintf (stderr
, "%s[%ld]: GSlice: ", pname
? pname
: "", (long)getpid());
1477 va_start (args
, format
);
1478 g_vfprintf (stderr
, format
, args
);
1480 fputs ("\n", stderr
);
1485 /* --- g-slice memory checker tree --- */
1486 typedef size_t SmcKType
; /* key type */
1487 typedef size_t SmcVType
; /* value type */
1492 static void smc_tree_insert (SmcKType key
,
1494 static gboolean
smc_tree_lookup (SmcKType key
,
1496 static gboolean
smc_tree_remove (SmcKType key
);
1499 /* --- g-slice memory checker implementation --- */
1501 smc_notify_alloc (void *pointer
,
1504 size_t address
= (size_t) pointer
;
1506 smc_tree_insert (address
, size
);
1511 smc_notify_ignore (void *pointer
)
1513 size_t address
= (size_t) pointer
;
1515 smc_tree_remove (address
);
1520 smc_notify_free (void *pointer
,
1523 size_t address
= (size_t) pointer
;
1528 return 1; /* ignore */
1529 found_one
= smc_tree_lookup (address
, &real_size
);
1532 g_fprintf (stderr
, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT
"\n", pointer
, size
);
1535 if (real_size
!= size
&& (real_size
|| size
))
1537 g_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
);
1540 if (!smc_tree_remove (address
))
1542 g_fprintf (stderr
, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT
"\n", pointer
, size
);
1545 return 1; /* all fine */
1548 /* --- g-slice memory checker tree implementation --- */
1549 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1550 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1551 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key address space per trunk, should distribute uniformly across BRANCH_COUNT */
1552 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1553 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1557 unsigned int n_entries
;
1560 static SmcBranch
**smc_tree_root
= NULL
;
1563 smc_tree_abort (int errval
)
1565 const char *syserr
= strerror (errval
);
1566 mem_error ("MemChecker: failure in debugging tree: %s", syserr
);
1569 static inline SmcEntry
*
1570 smc_tree_branch_grow_L (SmcBranch
*branch
,
1573 unsigned int old_size
= branch
->n_entries
* sizeof (branch
->entries
[0]);
1574 unsigned int new_size
= old_size
+ sizeof (branch
->entries
[0]);
1576 mem_assert (index
<= branch
->n_entries
);
1577 branch
->entries
= (SmcEntry
*) realloc (branch
->entries
, new_size
);
1578 if (!branch
->entries
)
1579 smc_tree_abort (errno
);
1580 entry
= branch
->entries
+ index
;
1581 memmove (entry
+ 1, entry
, (branch
->n_entries
- index
) * sizeof (entry
[0]));
1582 branch
->n_entries
+= 1;
1586 static inline SmcEntry
*
1587 smc_tree_branch_lookup_nearest_L (SmcBranch
*branch
,
1590 unsigned int n_nodes
= branch
->n_entries
, offs
= 0;
1591 SmcEntry
*check
= branch
->entries
;
1593 while (offs
< n_nodes
)
1595 unsigned int i
= (offs
+ n_nodes
) >> 1;
1596 check
= branch
->entries
+ i
;
1597 cmp
= key
< check
->key
? -1 : key
!= check
->key
;
1599 return check
; /* return exact match */
1602 else /* (cmp > 0) */
1605 /* check points at last mismatch, cmp > 0 indicates greater key */
1606 return cmp
> 0 ? check
+ 1 : check
; /* return insertion position for inexact match */
1610 smc_tree_insert (SmcKType key
,
1613 unsigned int ix0
, ix1
;
1616 g_mutex_lock (&smc_tree_mutex
);
1617 ix0
= SMC_TRUNK_HASH (key
);
1618 ix1
= SMC_BRANCH_HASH (key
);
1621 smc_tree_root
= calloc (SMC_TRUNK_COUNT
, sizeof (smc_tree_root
[0]));
1623 smc_tree_abort (errno
);
1625 if (!smc_tree_root
[ix0
])
1627 smc_tree_root
[ix0
] = calloc (SMC_BRANCH_COUNT
, sizeof (smc_tree_root
[0][0]));
1628 if (!smc_tree_root
[ix0
])
1629 smc_tree_abort (errno
);
1631 entry
= smc_tree_branch_lookup_nearest_L (&smc_tree_root
[ix0
][ix1
], key
);
1632 if (!entry
|| /* need create */
1633 entry
>= smc_tree_root
[ix0
][ix1
].entries
+ smc_tree_root
[ix0
][ix1
].n_entries
|| /* need append */
1634 entry
->key
!= key
) /* need insert */
1635 entry
= smc_tree_branch_grow_L (&smc_tree_root
[ix0
][ix1
], entry
- smc_tree_root
[ix0
][ix1
].entries
);
1637 entry
->value
= value
;
1638 g_mutex_unlock (&smc_tree_mutex
);
1642 smc_tree_lookup (SmcKType key
,
1645 SmcEntry
*entry
= NULL
;
1646 unsigned int ix0
= SMC_TRUNK_HASH (key
), ix1
= SMC_BRANCH_HASH (key
);
1647 gboolean found_one
= FALSE
;
1649 g_mutex_lock (&smc_tree_mutex
);
1650 if (smc_tree_root
&& smc_tree_root
[ix0
])
1652 entry
= smc_tree_branch_lookup_nearest_L (&smc_tree_root
[ix0
][ix1
], key
);
1654 entry
< smc_tree_root
[ix0
][ix1
].entries
+ smc_tree_root
[ix0
][ix1
].n_entries
&&
1658 *value_p
= entry
->value
;
1661 g_mutex_unlock (&smc_tree_mutex
);
1666 smc_tree_remove (SmcKType key
)
1668 unsigned int ix0
= SMC_TRUNK_HASH (key
), ix1
= SMC_BRANCH_HASH (key
);
1669 gboolean found_one
= FALSE
;
1670 g_mutex_lock (&smc_tree_mutex
);
1671 if (smc_tree_root
&& smc_tree_root
[ix0
])
1673 SmcEntry
*entry
= smc_tree_branch_lookup_nearest_L (&smc_tree_root
[ix0
][ix1
], key
);
1675 entry
< smc_tree_root
[ix0
][ix1
].entries
+ smc_tree_root
[ix0
][ix1
].n_entries
&&
1678 unsigned int i
= entry
- smc_tree_root
[ix0
][ix1
].entries
;
1679 smc_tree_root
[ix0
][ix1
].n_entries
-= 1;
1680 memmove (entry
, entry
+ 1, (smc_tree_root
[ix0
][ix1
].n_entries
- i
) * sizeof (entry
[0]));
1681 if (!smc_tree_root
[ix0
][ix1
].n_entries
)
1683 /* avoid useless pressure on the memory system */
1684 free (smc_tree_root
[ix0
][ix1
].entries
);
1685 smc_tree_root
[ix0
][ix1
].entries
= NULL
;
1690 g_mutex_unlock (&smc_tree_mutex
);
1694 #ifdef G_ENABLE_DEBUG
1696 g_slice_debug_tree_statistics (void)
1698 g_mutex_lock (&smc_tree_mutex
);
1701 unsigned int i
, j
, t
= 0, o
= 0, b
= 0, su
= 0, ex
= 0, en
= 4294967295u;
1703 for (i
= 0; i
< SMC_TRUNK_COUNT
; i
++)
1704 if (smc_tree_root
[i
])
1707 for (j
= 0; j
< SMC_BRANCH_COUNT
; j
++)
1708 if (smc_tree_root
[i
][j
].n_entries
)
1711 su
+= smc_tree_root
[i
][j
].n_entries
;
1712 en
= MIN (en
, smc_tree_root
[i
][j
].n_entries
);
1713 ex
= MAX (ex
, smc_tree_root
[i
][j
].n_entries
);
1715 else if (smc_tree_root
[i
][j
].entries
)
1716 o
++; /* formerly used, now empty */
1719 tf
= MAX (t
, 1.0); /* max(1) to be a valid divisor */
1720 bf
= MAX (b
, 1.0); /* max(1) to be a valid divisor */
1721 g_fprintf (stderr
, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t
, b
, o
);
1722 g_fprintf (stderr
, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1724 100.0 - (SMC_BRANCH_COUNT
- b
/ tf
) / (0.01 * SMC_BRANCH_COUNT
));
1725 g_fprintf (stderr
, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1729 g_fprintf (stderr
, "GSlice: MemChecker: root=NULL\n");
1730 g_mutex_unlock (&smc_tree_mutex
);
1732 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1733 * PID %CPU %MEM VSZ RSS COMMAND
1734 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1735 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1736 * 114017 103714 2354 344 0 108676 0
1737 * $ cat /proc/8887/status
1748 * (gdb) print g_slice_debug_tree_statistics ()
1749 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1750 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1751 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1754 #endif /* G_ENABLE_DEBUG */