1 /* GLIB sliced memory - fast concurrent memory chunk allocator
2 * Copyright (C) 2005 Tim Janik
3 *
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.
8 *
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.
13 *
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/>.
16 */
17 /* MT safe */
18
19 #include "config.h"
20 #include "glibconfig.h"
21
22 #if defined(HAVE_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE)
23 #define _XOPEN_SOURCE 600 /* posix_memalign() */
24 #endif
25 #include <stdlib.h> /* posix_memalign() */
26 #include <string.h>
27 #include <errno.h>
28
29 #ifdef G_OS_UNIX
30 #include <unistd.h> /* sysconf() */
31 #endif
32 #ifdef G_OS_WIN32
33 #include <windows.h>
34 #include <process.h>
35 #endif
36
37 #include <stdio.h> /* fputs */
38
39 #include "gslice.h"
40
41 #include "gmain.h"
42 #include "gmem.h" /* gslice.h */
43 #include "gstrfuncs.h"
44 #include "gutils.h"
45 #include "gtrashstack.h"
46 #include "gtestutils.h"
47 #include "gthread.h"
48 #include "gthreadprivate.h"
49 #include "glib_trace.h"
50 #include "gprintf.h"
51
52 #include "gvalgrind.h"
53
54 /**
55 * SECTION:memory_slices
56 * @title: Memory Slices
57 * @short_description: efficient way to allocate groups of equal-sized
58 * chunks of memory
59 *
60 * Memory slices provide a space-efficient and multi-processing scalable
61 * way to allocate equal-sized pieces of memory, just like the original
62 * #GMemChunks (from GLib 2.8), while avoiding their excessive
63 * memory-waste, scalability and performance problems.
64 *
65 * To achieve these goals, the slice allocator uses a sophisticated,
66 * layered design that has been inspired by Bonwick's slab allocator
67 * ([Bonwick94](http://citeseer.ist.psu.edu/bonwick94slab.html)
68 * Jeff Bonwick, The slab allocator: An object-caching kernel
69 * memory allocator. USENIX 1994, and
70 * [Bonwick01](http://citeseer.ist.psu.edu/bonwick01magazines.html)
71 * Bonwick and Jonathan Adams, Magazines and vmem: Extending the
72 * slab allocator to many cpu's and arbitrary resources. USENIX 2001)
73 *
74 * It uses posix_memalign() to optimize allocations of many equally-sized
75 * chunks, and has per-thread free lists (the so-called magazine layer)
76 * to quickly satisfy allocation requests of already known structure sizes.
77 * This is accompanied by extra caching logic to keep freed memory around
78 * for some time before returning it to the system. Memory that is unused
79 * due to alignment constraints is used for cache colorization (random
80 * distribution of chunk addresses) to improve CPU cache utilization. The
81 * caching layer of the slice allocator adapts itself to high lock contention
82 * to improve scalability.
83 *
84 * The slice allocator can allocate blocks as small as two pointers, and
85 * unlike malloc(), it does not reserve extra space per block. For large block
86 * sizes, g_slice_new() and g_slice_alloc() will automatically delegate to the
87 * system malloc() implementation. For newly written code it is recommended
88 * to use the new `g_slice` API instead of g_malloc() and
89 * friends, as long as objects are not resized during their lifetime and the
90 * object size used at allocation time is still available when freeing.
91 *
92 * Here is an example for using the slice allocator:
93 * |[<!-- language="C" -->
94 * gchar *mem[10000];
95 * gint i;
96 *
97 * // Allocate 10000 blocks.
98 * for (i = 0; i < 10000; i++)
99 * {
100 * mem[i] = g_slice_alloc (50);
101 *
102 * // Fill in the memory with some junk.
103 * for (j = 0; j < 50; j++)
104 * mem[i][j] = i * j;
105 * }
106 *
107 * // Now free all of the blocks.
108 * for (i = 0; i < 10000; i++)
109 * g_slice_free1 (50, mem[i]);
110 * ]|
111 *
112 * And here is an example for using the using the slice allocator
113 * with data structures:
114 * |[<!-- language="C" -->
115 * GRealArray *array;
116 *
117 * // Allocate one block, using the g_slice_new() macro.
118 * array = g_slice_new (GRealArray);
119 *
120 * // We can now use array just like a normal pointer to a structure.
121 * array->data = NULL;
122 * array->len = 0;
123 * array->alloc = 0;
124 * array->zero_terminated = (zero_terminated ? 1 : 0);
125 * array->clear = (clear ? 1 : 0);
126 * array->elt_size = elt_size;
127 *
128 * // We can free the block, so it can be reused.
129 * g_slice_free (GRealArray, array);
130 * ]|
131 */
132
133 /* the GSlice allocator is split up into 4 layers, roughly modelled after the slab
134 * allocator and magazine extensions as outlined in:
135 * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel
136 * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html
137 * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the
138 * slab allocator to many cpu's and arbitrary resources.
139 * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html
140 * the layers are:
141 * - the thread magazines. for each (aligned) chunk size, a magazine (a list)
142 * of recently freed and soon to be allocated chunks is maintained per thread.
143 * this way, most alloc/free requests can be quickly satisfied from per-thread
144 * free lists which only require one g_private_get() call to retrieve the
145 * thread handle.
146 * - the magazine cache. allocating and freeing chunks to/from threads only
147 * occurs at magazine sizes from a global depot of magazines. the depot
148 * maintaines a 15 second working set of allocated magazines, so full
149 * magazines are not allocated and released too often.
150 * the chunk size dependent magazine sizes automatically adapt (within limits,
151 * see [3]) to lock contention to properly scale performance across a variety
152 * of SMP systems.
153 * - the slab allocator. this allocator allocates slabs (blocks of memory) close
154 * to the system page size or multiples thereof which have to be page aligned.
155 * the blocks are divided into smaller chunks which are used to satisfy
156 * allocations from the upper layers. the space provided by the reminder of
157 * the chunk size division is used for cache colorization (random distribution
158 * of chunk addresses) to improve processor cache utilization. multiple slabs
159 * with the same chunk size are kept in a partially sorted ring to allow O(1)
160 * freeing and allocation of chunks (as long as the allocation of an entirely
161 * new slab can be avoided).
162 * - the page allocator. on most modern systems, posix_memalign(3) or
163 * memalign(3) should be available, so this is used to allocate blocks with
164 * system page size based alignments and sizes or multiples thereof.
165 * if no memalign variant is provided, valloc() is used instead and
166 * block sizes are limited to the system page size (no multiples thereof).
167 * as a fallback, on system without even valloc(), a malloc(3)-based page
168 * allocator with alloc-only behaviour is used.
169 *
170 * NOTES:
171 * [1] some systems memalign(3) implementations may rely on boundary tagging for
172 * the handed out memory chunks. to avoid excessive page-wise fragmentation,
173 * we reserve 2 * sizeof (void*) per block size for the systems memalign(3),
174 * specified in NATIVE_MALLOC_PADDING.
175 * [2] using the slab allocator alone already provides for a fast and efficient
176 * allocator, it doesn't properly scale beyond single-threaded uses though.
177 * also, the slab allocator implements eager free(3)-ing, i.e. does not
178 * provide any form of caching or working set maintenance. so if used alone,
179 * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs
180 * at certain thresholds.
181 * [3] magazine sizes are bound by an implementation specific minimum size and
182 * a chunk size specific maximum to limit magazine storage sizes to roughly
183 * 16KB.
184 * [4] allocating ca. 8 chunks per block/page keeps a good balance between
185 * external and internal fragmentation (<= 12.5%). [Bonwick94]
186 */
187
188 /* --- macros and constants --- */
189 #define LARGEALIGNMENT (256)
190 #define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */
191 #define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base)))
192 #define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */
193 #define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING)
194 #define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */
195 #define MIN_MAGAZINE_SIZE (4)
196 #define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */
197 #define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */
198 #define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1)
199 #define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */
200 #define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT)
201 #define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE)
202
203 /* optimized version of ALIGN (size, P2ALIGNMENT) */
204 #if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */
205 #define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7)
206 #elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */
207 #define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf)
208 #else
209 #define P2ALIGN(size) ALIGN (size, P2ALIGNMENT)
210 #endif
211
212 /* special helpers to avoid gmessage.c dependency */
213 static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
214 #define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
215
216 /* --- structures --- */
217 typedef struct _ChunkLink ChunkLink;
218 typedef struct _SlabInfo SlabInfo;
219 typedef struct _CachedMagazine CachedMagazine;
220 struct _ChunkLink {
221 ChunkLink *next;
222 ChunkLink *data;
223 };
224 struct _SlabInfo {
225 ChunkLink *chunks;
226 guint n_allocated;
227 SlabInfo *next, *prev;
228 };
229 typedef struct {
230 ChunkLink *chunks;
231 gsize count; /* approximative chunks list length */
232 } Magazine;
233 typedef struct {
234 Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */
235 Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */
236 } ThreadMemory;
237 typedef struct {
238 gboolean always_malloc;
239 gboolean bypass_magazines;
240 gboolean debug_blocks;
241 gsize working_set_msecs;
242 guint color_increment;
243 } SliceConfig;
244 typedef struct {
245 /* const after initialization */
246 gsize min_page_size, max_page_size;
247 SliceConfig config;
248 gsize max_slab_chunk_size_for_magazine_cache;
249 /* magazine cache */
250 GMutex magazine_mutex;
251 ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */
252 guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */
253 gint mutex_counter;
254 guint stamp_counter;
255 guint last_stamp;
256 /* slab allocator */
257 GMutex slab_mutex;
258 SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */
259 guint color_accu;
260 } Allocator;
261
262 /* --- g-slice prototypes --- */
263 static gpointer slab_allocator_alloc_chunk (gsize chunk_size);
264 static void slab_allocator_free_chunk (gsize chunk_size,
265 gpointer mem);
266 static void private_thread_memory_cleanup (gpointer data);
267 static gpointer allocator_memalign (gsize alignment,
268 gsize memsize);
269 static void allocator_memfree (gsize memsize,
270 gpointer mem);
271 static inline void magazine_cache_update_stamp (void);
272 static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
273 guint ix);
274
275 /* --- g-slice memory checker --- */
276 static void smc_notify_alloc (void *pointer,
277 size_t size);
278 static int smc_notify_free (void *pointer,
279 size_t size);
280
281 /* --- variables --- */
282 static GPrivate private_thread_memory = G_PRIVATE_INIT (private_thread_memory_cleanup);
283 static gsize sys_page_size = 0;
284 static Allocator allocator[1] = { { 0, }, };
285 static SliceConfig slice_config = {
286 FALSE, /* always_malloc */
287 FALSE, /* bypass_magazines */
288 FALSE, /* debug_blocks */
289 15 * 1000, /* working_set_msecs */
290 1, /* color increment, alt: 0x7fffffff */
291 };
292 static GMutex smc_tree_mutex; /* mutex for G_SLICE=debug-blocks */
293
294 /* --- auxiliary functions --- */
295 void
g_slice_set_config(GSliceConfig ckey,gint64 value)296 g_slice_set_config (GSliceConfig ckey,
297 gint64 value)
298 {
299 g_return_if_fail (sys_page_size == 0);
300 switch (ckey)
301 {
302 case G_SLICE_CONFIG_ALWAYS_MALLOC:
303 slice_config.always_malloc = value != 0;
304 break;
305 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
306 slice_config.bypass_magazines = value != 0;
307 break;
308 case G_SLICE_CONFIG_WORKING_SET_MSECS:
309 slice_config.working_set_msecs = value;
310 break;
311 case G_SLICE_CONFIG_COLOR_INCREMENT:
312 slice_config.color_increment = value;
313 break;
314 default: ;
315 }
316 }
317
318 gint64
g_slice_get_config(GSliceConfig ckey)319 g_slice_get_config (GSliceConfig ckey)
320 {
321 switch (ckey)
322 {
323 case G_SLICE_CONFIG_ALWAYS_MALLOC:
324 return slice_config.always_malloc;
325 case G_SLICE_CONFIG_BYPASS_MAGAZINES:
326 return slice_config.bypass_magazines;
327 case G_SLICE_CONFIG_WORKING_SET_MSECS:
328 return slice_config.working_set_msecs;
329 case G_SLICE_CONFIG_CHUNK_SIZES:
330 return MAX_SLAB_INDEX (allocator);
331 case G_SLICE_CONFIG_COLOR_INCREMENT:
332 return slice_config.color_increment;
333 default:
334 return 0;
335 }
336 }
337
338 gint64*
g_slice_get_config_state(GSliceConfig ckey,gint64 address,guint * n_values)339 g_slice_get_config_state (GSliceConfig ckey,
340 gint64 address,
341 guint *n_values)
342 {
343 guint i = 0;
344 g_return_val_if_fail (n_values != NULL, NULL);
345 *n_values = 0;
346 switch (ckey)
347 {
348 gint64 array[64];
349 case G_SLICE_CONFIG_CONTENTION_COUNTER:
350 array[i++] = SLAB_CHUNK_SIZE (allocator, address);
351 array[i++] = allocator->contention_counters[address];
352 array[i++] = allocator_get_magazine_threshold (allocator, address);
353 *n_values = i;
354 return g_memdup2 (array, sizeof (array[0]) * *n_values);
355 default:
356 return NULL;
357 }
358 }
359
360 static void
slice_config_init(SliceConfig * config)361 slice_config_init (SliceConfig *config)
362 {
363 const gchar *val;
364 gchar *val_allocated = NULL;
365
366 *config = slice_config;
367
368 /* Note that the empty string (`G_SLICE=""`) is treated differently from the
369 * envvar being unset. In the latter case, we also check whether running under
370 * valgrind. */
371 #ifndef G_OS_WIN32
372 val = g_getenv ("G_SLICE");
373 #else
374 /* The win32 implementation of g_getenv() has to do UTF-8 ↔ UTF-16 conversions
375 * which use the slice allocator, leading to deadlock. Use a simple in-place
376 * implementation here instead.
377 *
378 * Ignore references to other environment variables: only support values which
379 * are a combination of always-malloc and debug-blocks. */
380 {
381
382 wchar_t wvalue[128]; /* at least big enough for `always-malloc,debug-blocks` */
383 int len;
384
385 len = GetEnvironmentVariableW (L"G_SLICE", wvalue, G_N_ELEMENTS (wvalue));
386
387 if (len == 0)
388 {
389 if (GetLastError () == ERROR_ENVVAR_NOT_FOUND)
390 val = NULL;
391 else
392 val = "";
393 }
394 else if (len >= G_N_ELEMENTS (wvalue))
395 {
396 /* @wvalue isn’t big enough. Give up. */
397 g_warning ("Unsupported G_SLICE value");
398 val = NULL;
399 }
400 else
401 {
402 /* it’s safe to use g_utf16_to_utf8() here as it only allocates using
403 * malloc() rather than GSlice */
404 val = val_allocated = g_utf16_to_utf8 (wvalue, -1, NULL, NULL, NULL);
405 }
406
407 }
408 #endif /* G_OS_WIN32 */
409
410 if (val != NULL)
411 {
412 gint flags;
413 const GDebugKey keys[] = {
414 { "always-malloc", 1 << 0 },
415 { "debug-blocks", 1 << 1 },
416 };
417
418 flags = g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
419 if (flags & (1 << 0))
420 config->always_malloc = TRUE;
421 if (flags & (1 << 1))
422 config->debug_blocks = TRUE;
423 }
424 else
425 {
426 /* G_SLICE was not specified, so check if valgrind is running and
427 * disable ourselves if it is.
428 *
429 * This way it's possible to force gslice to be enabled under
430 * valgrind just by setting G_SLICE to the empty string.
431 */
432 #ifdef ENABLE_VALGRIND
433 if (RUNNING_ON_VALGRIND)
434 config->always_malloc = TRUE;
435 #endif
436 }
437
438 g_free (val_allocated);
439 }
440
441 static void
g_slice_init_nomessage(void)442 g_slice_init_nomessage (void)
443 {
444 /* we may not use g_error() or friends here */
445 mem_assert (sys_page_size == 0);
446 mem_assert (MIN_MAGAZINE_SIZE >= 4);
447
448 #ifdef G_OS_WIN32
449 {
450 SYSTEM_INFO system_info;
451 GetSystemInfo (&system_info);
452 sys_page_size = system_info.dwPageSize;
453 }
454 #else
455 sys_page_size = sysconf (_SC_PAGESIZE); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */
456 #endif
457 mem_assert (sys_page_size >= 2 * LARGEALIGNMENT);
458 mem_assert ((sys_page_size & (sys_page_size - 1)) == 0);
459 slice_config_init (&allocator->config);
460 allocator->min_page_size = sys_page_size;
461 #if HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN
462 /* allow allocation of pages up to 8KB (with 8KB alignment).
463 * this is useful because many medium to large sized structures
464 * fit less than 8 times (see [4]) into 4KB pages.
465 * we allow very small page sizes here, to reduce wastage in
466 * threads if only small allocations are required (this does
467 * bear the risk of increasing allocation times and fragmentation
468 * though).
469 */
470 allocator->min_page_size = MAX (allocator->min_page_size, 4096);
471 allocator->max_page_size = MAX (allocator->min_page_size, 8192);
472 allocator->min_page_size = MIN (allocator->min_page_size, 128);
473 #else
474 /* we can only align to system page size */
475 allocator->max_page_size = sys_page_size;
476 #endif
477 if (allocator->config.always_malloc)
478 {
479 allocator->contention_counters = NULL;
480 allocator->magazines = NULL;
481 allocator->slab_stack = NULL;
482 }
483 else
484 {
485 allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator));
486 allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator));
487 allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
488 }
489
490 allocator->mutex_counter = 0;
491 allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
492 allocator->last_stamp = 0;
493 allocator->color_accu = 0;
494 magazine_cache_update_stamp();
495 /* values cached for performance reasons */
496 allocator->max_slab_chunk_size_for_magazine_cache = MAX_SLAB_CHUNK_SIZE (allocator);
497 if (allocator->config.always_malloc || allocator->config.bypass_magazines)
498 allocator->max_slab_chunk_size_for_magazine_cache = 0; /* non-optimized cases */
499 }
500
501 static inline guint
allocator_categorize(gsize aligned_chunk_size)502 allocator_categorize (gsize aligned_chunk_size)
503 {
504 /* speed up the likely path */
505 if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache))
506 return 1; /* use magazine cache */
507
508 if (!allocator->config.always_malloc &&
509 aligned_chunk_size &&
510 aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator))
511 {
512 if (allocator->config.bypass_magazines)
513 return 2; /* use slab allocator, see [2] */
514 return 1; /* use magazine cache */
515 }
516 return 0; /* use malloc() */
517 }
518
519 static inline void
g_mutex_lock_a(GMutex * mutex,guint * contention_counter)520 g_mutex_lock_a (GMutex *mutex,
521 guint *contention_counter)
522 {
523 gboolean contention = FALSE;
524 if (!g_mutex_trylock (mutex))
525 {
526 g_mutex_lock (mutex);
527 contention = TRUE;
528 }
529 if (contention)
530 {
531 allocator->mutex_counter++;
532 if (allocator->mutex_counter >= 1) /* quickly adapt to contention */
533 {
534 allocator->mutex_counter = 0;
535 *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE);
536 }
537 }
538 else /* !contention */
539 {
540 allocator->mutex_counter--;
541 if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */
542 {
543 allocator->mutex_counter = 0;
544 *contention_counter = MAX (*contention_counter, 1) - 1;
545 }
546 }
547 }
548
549 static inline ThreadMemory*
thread_memory_from_self(void)550 thread_memory_from_self (void)
551 {
552 ThreadMemory *tmem = g_private_get (&private_thread_memory);
553 if (G_UNLIKELY (!tmem))
554 {
555 static GMutex init_mutex;
556 guint n_magazines;
557
558 g_mutex_lock (&init_mutex);
559 if G_UNLIKELY (sys_page_size == 0)
560 g_slice_init_nomessage ();
561 g_mutex_unlock (&init_mutex);
562
563 n_magazines = MAX_SLAB_INDEX (allocator);
564 tmem = g_private_set_alloc0 (&private_thread_memory, sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
565 tmem->magazine1 = (Magazine*) (tmem + 1);
566 tmem->magazine2 = &tmem->magazine1[n_magazines];
567 }
568 return tmem;
569 }
570
571 static inline ChunkLink*
magazine_chain_pop_head(ChunkLink ** magazine_chunks)572 magazine_chain_pop_head (ChunkLink **magazine_chunks)
573 {
574 /* magazine chains are linked via ChunkLink->next.
575 * each ChunkLink->data of the toplevel chain may point to a subchain,
576 * linked via ChunkLink->next. ChunkLink->data of the subchains just
577 * contains uninitialized junk.
578 */
579 ChunkLink *chunk = (*magazine_chunks)->data;
580 if (G_UNLIKELY (chunk))
581 {
582 /* allocating from freed list */
583 (*magazine_chunks)->data = chunk->next;
584 }
585 else
586 {
587 chunk = *magazine_chunks;
588 *magazine_chunks = chunk->next;
589 }
590 return chunk;
591 }
592
593 #if 0 /* useful for debugging */
594 static guint
595 magazine_count (ChunkLink *head)
596 {
597 guint count = 0;
598 if (!head)
599 return 0;
600 while (head)
601 {
602 ChunkLink *child = head->data;
603 count += 1;
604 for (child = head->data; child; child = child->next)
605 count += 1;
606 head = head->next;
607 }
608 return count;
609 }
610 #endif
611
612 static inline gsize
allocator_get_magazine_threshold(Allocator * allocator,guint ix)613 allocator_get_magazine_threshold (Allocator *allocator,
614 guint ix)
615 {
616 /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE,
617 * which is required by the implementation. also, for moderately sized chunks
618 * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number
619 * of chunks available per page/2 to avoid excessive traffic in the magazine
620 * cache for small to medium sized structures.
621 * the upper bound of the magazine size is effectively provided by
622 * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that
623 * the content of a single magazine doesn't exceed ca. 16KB.
624 */
625 gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
626 guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator->max_page_size / MAX (5 * chunk_size, 5 * 32));
627 guint contention_counter = allocator->contention_counters[ix];
628 if (G_UNLIKELY (contention_counter)) /* single CPU bias */
629 {
630 /* adapt contention counter thresholds to chunk sizes */
631 contention_counter = contention_counter * 64 / chunk_size;
632 threshold = MAX (threshold, contention_counter);
633 }
634 return threshold;
635 }
636
637 /* --- magazine cache --- */
638 static inline void
magazine_cache_update_stamp(void)639 magazine_cache_update_stamp (void)
640 {
641 if (allocator->stamp_counter >= MAX_STAMP_COUNTER)
642 {
643 gint64 now_us = g_get_real_time ();
644 allocator->last_stamp = now_us / 1000; /* milli seconds */
645 allocator->stamp_counter = 0;
646 }
647 else
648 allocator->stamp_counter++;
649 }
650
651 static inline ChunkLink*
magazine_chain_prepare_fields(ChunkLink * magazine_chunks)652 magazine_chain_prepare_fields (ChunkLink *magazine_chunks)
653 {
654 ChunkLink *chunk1;
655 ChunkLink *chunk2;
656 ChunkLink *chunk3;
657 ChunkLink *chunk4;
658 /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */
659 /* ensure a magazine with at least 4 unused data pointers */
660 chunk1 = magazine_chain_pop_head (&magazine_chunks);
661 chunk2 = magazine_chain_pop_head (&magazine_chunks);
662 chunk3 = magazine_chain_pop_head (&magazine_chunks);
663 chunk4 = magazine_chain_pop_head (&magazine_chunks);
664 chunk4->next = magazine_chunks;
665 chunk3->next = chunk4;
666 chunk2->next = chunk3;
667 chunk1->next = chunk2;
668 return chunk1;
669 }
670
671 /* access the first 3 fields of a specially prepared magazine chain */
672 #define magazine_chain_prev(mc) ((mc)->data)
673 #define magazine_chain_stamp(mc) ((mc)->next->data)
674 #define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data)
675 #define magazine_chain_next(mc) ((mc)->next->next->data)
676 #define magazine_chain_count(mc) ((mc)->next->next->next->data)
677
678 static void
magazine_cache_trim(Allocator * allocator,guint ix,guint stamp)679 magazine_cache_trim (Allocator *allocator,
680 guint ix,
681 guint stamp)
682 {
683 /* g_mutex_lock (allocator->mutex); done by caller */
684 /* trim magazine cache from tail */
685 ChunkLink *current = magazine_chain_prev (allocator->magazines[ix]);
686 ChunkLink *trash = NULL;
687 while (!G_APPROX_VALUE(stamp, magazine_chain_uint_stamp (current),
688 allocator->config.working_set_msecs))
689 {
690 /* unlink */
691 ChunkLink *prev = magazine_chain_prev (current);
692 ChunkLink *next = magazine_chain_next (current);
693 magazine_chain_next (prev) = next;
694 magazine_chain_prev (next) = prev;
695 /* clear special fields, put on trash stack */
696 magazine_chain_next (current) = NULL;
697 magazine_chain_count (current) = NULL;
698 magazine_chain_stamp (current) = NULL;
699 magazine_chain_prev (current) = trash;
700 trash = current;
701 /* fixup list head if required */
702 if (current == allocator->magazines[ix])
703 {
704 allocator->magazines[ix] = NULL;
705 break;
706 }
707 current = prev;
708 }
709 g_mutex_unlock (&allocator->magazine_mutex);
710 /* free trash */
711 if (trash)
712 {
713 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
714 g_mutex_lock (&allocator->slab_mutex);
715 while (trash)
716 {
717 current = trash;
718 trash = magazine_chain_prev (current);
719 magazine_chain_prev (current) = NULL; /* clear special field */
720 while (current)
721 {
722 ChunkLink *chunk = magazine_chain_pop_head (¤t);
723 slab_allocator_free_chunk (chunk_size, chunk);
724 }
725 }
726 g_mutex_unlock (&allocator->slab_mutex);
727 }
728 }
729
730 static void
magazine_cache_push_magazine(guint ix,ChunkLink * magazine_chunks,gsize count)731 magazine_cache_push_magazine (guint ix,
732 ChunkLink *magazine_chunks,
733 gsize count) /* must be >= MIN_MAGAZINE_SIZE */
734 {
735 ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks);
736 ChunkLink *next, *prev;
737 g_mutex_lock (&allocator->magazine_mutex);
738 /* add magazine at head */
739 next = allocator->magazines[ix];
740 if (next)
741 prev = magazine_chain_prev (next);
742 else
743 next = prev = current;
744 magazine_chain_next (prev) = current;
745 magazine_chain_prev (next) = current;
746 magazine_chain_prev (current) = prev;
747 magazine_chain_next (current) = next;
748 magazine_chain_count (current) = (gpointer) count;
749 /* stamp magazine */
750 magazine_cache_update_stamp();
751 magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
752 allocator->magazines[ix] = current;
753 /* free old magazines beyond a certain threshold */
754 magazine_cache_trim (allocator, ix, allocator->last_stamp);
755 /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */
756 }
757
758 static ChunkLink*
magazine_cache_pop_magazine(guint ix,gsize * countp)759 magazine_cache_pop_magazine (guint ix,
760 gsize *countp)
761 {
762 g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]);
763 if (!allocator->magazines[ix])
764 {
765 guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix);
766 gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
767 ChunkLink *chunk, *head;
768 g_mutex_unlock (&allocator->magazine_mutex);
769 g_mutex_lock (&allocator->slab_mutex);
770 head = slab_allocator_alloc_chunk (chunk_size);
771 head->data = NULL;
772 chunk = head;
773 for (i = 1; i < magazine_threshold; i++)
774 {
775 chunk->next = slab_allocator_alloc_chunk (chunk_size);
776 chunk = chunk->next;
777 chunk->data = NULL;
778 }
779 chunk->next = NULL;
780 g_mutex_unlock (&allocator->slab_mutex);
781 *countp = i;
782 return head;
783 }
784 else
785 {
786 ChunkLink *current = allocator->magazines[ix];
787 ChunkLink *prev = magazine_chain_prev (current);
788 ChunkLink *next = magazine_chain_next (current);
789 /* unlink */
790 magazine_chain_next (prev) = next;
791 magazine_chain_prev (next) = prev;
792 allocator->magazines[ix] = next == current ? NULL : next;
793 g_mutex_unlock (&allocator->magazine_mutex);
794 /* clear special fields and hand out */
795 *countp = (gsize) magazine_chain_count (current);
796 magazine_chain_prev (current) = NULL;
797 magazine_chain_next (current) = NULL;
798 magazine_chain_count (current) = NULL;
799 magazine_chain_stamp (current) = NULL;
800 return current;
801 }
802 }
803
804 /* --- thread magazines --- */
805 static void
private_thread_memory_cleanup(gpointer data)806 private_thread_memory_cleanup (gpointer data)
807 {
808 ThreadMemory *tmem = data;
809 const guint n_magazines = MAX_SLAB_INDEX (allocator);
810 guint ix;
811 for (ix = 0; ix < n_magazines; ix++)
812 {
813 Magazine *mags[2];
814 guint j;
815 mags[0] = &tmem->magazine1[ix];
816 mags[1] = &tmem->magazine2[ix];
817 for (j = 0; j < 2; j++)
818 {
819 Magazine *mag = mags[j];
820 if (mag->count >= MIN_MAGAZINE_SIZE)
821 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
822 else
823 {
824 const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix);
825 g_mutex_lock (&allocator->slab_mutex);
826 while (mag->chunks)
827 {
828 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
829 slab_allocator_free_chunk (chunk_size, chunk);
830 }
831 g_mutex_unlock (&allocator->slab_mutex);
832 }
833 }
834 }
835 g_free (tmem);
836 }
837
838 static void
thread_memory_magazine1_reload(ThreadMemory * tmem,guint ix)839 thread_memory_magazine1_reload (ThreadMemory *tmem,
840 guint ix)
841 {
842 Magazine *mag = &tmem->magazine1[ix];
843 mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */
844 mag->count = 0;
845 mag->chunks = magazine_cache_pop_magazine (ix, &mag->count);
846 }
847
848 static void
thread_memory_magazine2_unload(ThreadMemory * tmem,guint ix)849 thread_memory_magazine2_unload (ThreadMemory *tmem,
850 guint ix)
851 {
852 Magazine *mag = &tmem->magazine2[ix];
853 magazine_cache_push_magazine (ix, mag->chunks, mag->count);
854 mag->chunks = NULL;
855 mag->count = 0;
856 }
857
858 static inline void
thread_memory_swap_magazines(ThreadMemory * tmem,guint ix)859 thread_memory_swap_magazines (ThreadMemory *tmem,
860 guint ix)
861 {
862 Magazine xmag = tmem->magazine1[ix];
863 tmem->magazine1[ix] = tmem->magazine2[ix];
864 tmem->magazine2[ix] = xmag;
865 }
866
867 static inline gboolean
thread_memory_magazine1_is_empty(ThreadMemory * tmem,guint ix)868 thread_memory_magazine1_is_empty (ThreadMemory *tmem,
869 guint ix)
870 {
871 return tmem->magazine1[ix].chunks == NULL;
872 }
873
874 static inline gboolean
thread_memory_magazine2_is_full(ThreadMemory * tmem,guint ix)875 thread_memory_magazine2_is_full (ThreadMemory *tmem,
876 guint ix)
877 {
878 return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix);
879 }
880
881 static inline gpointer
thread_memory_magazine1_alloc(ThreadMemory * tmem,guint ix)882 thread_memory_magazine1_alloc (ThreadMemory *tmem,
883 guint ix)
884 {
885 Magazine *mag = &tmem->magazine1[ix];
886 ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks);
887 if (G_LIKELY (mag->count > 0))
888 mag->count--;
889 return chunk;
890 }
891
892 static inline void
thread_memory_magazine2_free(ThreadMemory * tmem,guint ix,gpointer mem)893 thread_memory_magazine2_free (ThreadMemory *tmem,
894 guint ix,
895 gpointer mem)
896 {
897 Magazine *mag = &tmem->magazine2[ix];
898 ChunkLink *chunk = mem;
899 chunk->data = NULL;
900 chunk->next = mag->chunks;
901 mag->chunks = chunk;
902 mag->count++;
903 }
904
905 /* --- API functions --- */
906
907 /**
908 * g_slice_new:
909 * @type: the type to allocate, typically a structure name
910 *
911 * A convenience macro to allocate a block of memory from the
912 * slice allocator.
913 *
914 * It calls g_slice_alloc() with `sizeof (@type)` and casts the
915 * returned pointer to a pointer of the given type, avoiding a type
916 * cast in the source code. Note that the underlying slice allocation
917 * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
918 * environment variable.
919 *
920 * This can never return %NULL as the minimum allocation size from
921 * `sizeof (@type)` is 1 byte.
922 *
923 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
924 * to @type
925 *
926 * Since: 2.10
927 */
928
929 /**
930 * g_slice_new0:
931 * @type: the type to allocate, typically a structure name
932 *
933 * A convenience macro to allocate a block of memory from the
934 * slice allocator and set the memory to 0.
935 *
936 * It calls g_slice_alloc0() with `sizeof (@type)`
937 * and casts the returned pointer to a pointer of the given type,
938 * avoiding a type cast in the source code.
939 * Note that the underlying slice allocation mechanism can
940 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
941 * environment variable.
942 *
943 * This can never return %NULL as the minimum allocation size from
944 * `sizeof (@type)` is 1 byte.
945 *
946 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
947 * to @type
948 *
949 * Since: 2.10
950 */
951
952 /**
953 * g_slice_dup:
954 * @type: the type to duplicate, typically a structure name
955 * @mem: (not nullable): the memory to copy into the allocated block
956 *
957 * A convenience macro to duplicate a block of memory using
958 * the slice allocator.
959 *
960 * It calls g_slice_copy() with `sizeof (@type)`
961 * and casts the returned pointer to a pointer of the given type,
962 * avoiding a type cast in the source code.
963 * Note that the underlying slice allocation mechanism can
964 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
965 * environment variable.
966 *
967 * This can never return %NULL.
968 *
969 * Returns: (not nullable): a pointer to the allocated block, cast to a pointer
970 * to @type
971 *
972 * Since: 2.14
973 */
974
975 /**
976 * g_slice_free:
977 * @type: the type of the block to free, typically a structure name
978 * @mem: a pointer to the block to free
979 *
980 * A convenience macro to free a block of memory that has
981 * been allocated from the slice allocator.
982 *
983 * It calls g_slice_free1() using `sizeof (type)`
984 * as the block size.
985 * Note that the exact release behaviour can be changed with the
986 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
987 * [`G_SLICE`][G_SLICE] for related debugging options.
988 *
989 * If @mem is %NULL, this macro does nothing.
990 *
991 * Since: 2.10
992 */
993
994 /**
995 * g_slice_free_chain:
996 * @type: the type of the @mem_chain blocks
997 * @mem_chain: a pointer to the first block of the chain
998 * @next: the field name of the next pointer in @type
999 *
1000 * Frees a linked list of memory blocks of structure type @type.
1001 * The memory blocks must be equal-sized, allocated via
1002 * g_slice_alloc() or g_slice_alloc0() and linked together by
1003 * a @next pointer (similar to #GSList). The name of the
1004 * @next field in @type is passed as third argument.
1005 * Note that the exact release behaviour can be changed with the
1006 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
1007 * [`G_SLICE`][G_SLICE] for related debugging options.
1008 *
1009 * If @mem_chain is %NULL, this function does nothing.
1010 *
1011 * Since: 2.10
1012 */
1013
1014 /**
1015 * g_slice_alloc:
1016 * @block_size: the number of bytes to allocate
1017 *
1018 * Allocates a block of memory from the slice allocator.
1019 * The block address handed out can be expected to be aligned
1020 * to at least 1 * sizeof (void*),
1021 * though in general slices are 2 * sizeof (void*) bytes aligned,
1022 * if a malloc() fallback implementation is used instead,
1023 * the alignment may be reduced in a libc dependent fashion.
1024 * Note that the underlying slice allocation mechanism can
1025 * be changed with the [`G_SLICE=always-malloc`][G_SLICE]
1026 * environment variable.
1027 *
1028 * Returns: a pointer to the allocated memory block, which will be %NULL if and
1029 * only if @mem_size is 0
1030 *
1031 * Since: 2.10
1032 */
1033 gpointer
g_slice_alloc(gsize mem_size)1034 g_slice_alloc (gsize mem_size)
1035 {
1036 ThreadMemory *tmem;
1037 gsize chunk_size;
1038 gpointer mem;
1039 guint acat;
1040
1041 /* This gets the private structure for this thread. If the private
1042 * structure does not yet exist, it is created.
1043 *
1044 * This has a side effect of causing GSlice to be initialised, so it
1045 * must come first.
1046 */
1047 tmem = thread_memory_from_self ();
1048
1049 chunk_size = P2ALIGN (mem_size);
1050 acat = allocator_categorize (chunk_size);
1051 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
1052 {
1053 guint ix = SLAB_INDEX (allocator, chunk_size);
1054 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
1055 {
1056 thread_memory_swap_magazines (tmem, ix);
1057 if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix)))
1058 thread_memory_magazine1_reload (tmem, ix);
1059 }
1060 mem = thread_memory_magazine1_alloc (tmem, ix);
1061 }
1062 else if (acat == 2) /* allocate through slab allocator */
1063 {
1064 g_mutex_lock (&allocator->slab_mutex);
1065 mem = slab_allocator_alloc_chunk (chunk_size);
1066 g_mutex_unlock (&allocator->slab_mutex);
1067 }
1068 else /* delegate to system malloc */
1069 mem = g_malloc (mem_size);
1070 if (G_UNLIKELY (allocator->config.debug_blocks))
1071 smc_notify_alloc (mem, mem_size);
1072
1073 TRACE (GLIB_SLICE_ALLOC((void*)mem, mem_size));
1074
1075 return mem;
1076 }
1077
1078 /**
1079 * g_slice_alloc0:
1080 * @block_size: the number of bytes to allocate
1081 *
1082 * Allocates a block of memory via g_slice_alloc() and initializes
1083 * the returned memory to 0. Note that the underlying slice allocation
1084 * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE]
1085 * environment variable.
1086 *
1087 * Returns: a pointer to the allocated block, which will be %NULL if and only
1088 * if @mem_size is 0
1089 *
1090 * Since: 2.10
1091 */
1092 gpointer
g_slice_alloc0(gsize mem_size)1093 g_slice_alloc0 (gsize mem_size)
1094 {
1095 gpointer mem = g_slice_alloc (mem_size);
1096 if (mem)
1097 memset (mem, 0, mem_size);
1098 return mem;
1099 }
1100
1101 /**
1102 * g_slice_copy:
1103 * @block_size: the number of bytes to allocate
1104 * @mem_block: the memory to copy
1105 *
1106 * Allocates a block of memory from the slice allocator
1107 * and copies @block_size bytes into it from @mem_block.
1108 *
1109 * @mem_block must be non-%NULL if @block_size is non-zero.
1110 *
1111 * Returns: a pointer to the allocated memory block, which will be %NULL if and
1112 * only if @mem_size is 0
1113 *
1114 * Since: 2.14
1115 */
1116 gpointer
g_slice_copy(gsize mem_size,gconstpointer mem_block)1117 g_slice_copy (gsize mem_size,
1118 gconstpointer mem_block)
1119 {
1120 gpointer mem = g_slice_alloc (mem_size);
1121 if (mem)
1122 memcpy (mem, mem_block, mem_size);
1123 return mem;
1124 }
1125
1126 /**
1127 * g_slice_free1:
1128 * @block_size: the size of the block
1129 * @mem_block: a pointer to the block to free
1130 *
1131 * Frees a block of memory.
1132 *
1133 * The memory must have been allocated via g_slice_alloc() or
1134 * g_slice_alloc0() and the @block_size has to match the size
1135 * specified upon allocation. Note that the exact release behaviour
1136 * can be changed with the [`G_DEBUG=gc-friendly`][G_DEBUG] environment
1137 * variable, also see [`G_SLICE`][G_SLICE] for related debugging options.
1138 *
1139 * If @mem_block is %NULL, this function does nothing.
1140 *
1141 * Since: 2.10
1142 */
1143 void
g_slice_free1(gsize mem_size,gpointer mem_block)1144 g_slice_free1 (gsize mem_size,
1145 gpointer mem_block)
1146 {
1147 gsize chunk_size = P2ALIGN (mem_size);
1148 guint acat = allocator_categorize (chunk_size);
1149 if (G_UNLIKELY (!mem_block))
1150 return;
1151 if (G_UNLIKELY (allocator->config.debug_blocks) &&
1152 !smc_notify_free (mem_block, mem_size))
1153 abort();
1154 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
1155 {
1156 ThreadMemory *tmem = thread_memory_from_self();
1157 guint ix = SLAB_INDEX (allocator, chunk_size);
1158 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
1159 {
1160 thread_memory_swap_magazines (tmem, ix);
1161 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
1162 thread_memory_magazine2_unload (tmem, ix);
1163 }
1164 if (G_UNLIKELY (g_mem_gc_friendly))
1165 memset (mem_block, 0, chunk_size);
1166 thread_memory_magazine2_free (tmem, ix, mem_block);
1167 }
1168 else if (acat == 2) /* allocate through slab allocator */
1169 {
1170 if (G_UNLIKELY (g_mem_gc_friendly))
1171 memset (mem_block, 0, chunk_size);
1172 g_mutex_lock (&allocator->slab_mutex);
1173 slab_allocator_free_chunk (chunk_size, mem_block);
1174 g_mutex_unlock (&allocator->slab_mutex);
1175 }
1176 else /* delegate to system malloc */
1177 {
1178 if (G_UNLIKELY (g_mem_gc_friendly))
1179 memset (mem_block, 0, mem_size);
1180 g_free (mem_block);
1181 }
1182 TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size));
1183 }
1184
1185 /**
1186 * g_slice_free_chain_with_offset:
1187 * @block_size: the size of the blocks
1188 * @mem_chain: a pointer to the first block of the chain
1189 * @next_offset: the offset of the @next field in the blocks
1190 *
1191 * Frees a linked list of memory blocks of structure type @type.
1192 *
1193 * The memory blocks must be equal-sized, allocated via
1194 * g_slice_alloc() or g_slice_alloc0() and linked together by a
1195 * @next pointer (similar to #GSList). The offset of the @next
1196 * field in each block is passed as third argument.
1197 * Note that the exact release behaviour can be changed with the
1198 * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see
1199 * [`G_SLICE`][G_SLICE] for related debugging options.
1200 *
1201 * If @mem_chain is %NULL, this function does nothing.
1202 *
1203 * Since: 2.10
1204 */
1205 void
g_slice_free_chain_with_offset(gsize mem_size,gpointer mem_chain,gsize next_offset)1206 g_slice_free_chain_with_offset (gsize mem_size,
1207 gpointer mem_chain,
1208 gsize next_offset)
1209 {
1210 gpointer slice = mem_chain;
1211 /* while the thread magazines and the magazine cache are implemented so that
1212 * they can easily be extended to allow for free lists containing more free
1213 * lists for the first level nodes, which would allow O(1) freeing in this
1214 * function, the benefit of such an extension is questionable, because:
1215 * - the magazine size counts will become mere lower bounds which confuses
1216 * the code adapting to lock contention;
1217 * - freeing a single node to the thread magazines is very fast, so this
1218 * O(list_length) operation is multiplied by a fairly small factor;
1219 * - memory usage histograms on larger applications seem to indicate that
1220 * the amount of released multi node lists is negligible in comparison
1221 * to single node releases.
1222 * - the major performance bottle neck, namely g_private_get() or
1223 * g_mutex_lock()/g_mutex_unlock() has already been moved out of the
1224 * inner loop for freeing chained slices.
1225 */
1226 gsize chunk_size = P2ALIGN (mem_size);
1227 guint acat = allocator_categorize (chunk_size);
1228 if (G_LIKELY (acat == 1)) /* allocate through magazine layer */
1229 {
1230 ThreadMemory *tmem = thread_memory_from_self();
1231 guint ix = SLAB_INDEX (allocator, chunk_size);
1232 while (slice)
1233 {
1234 guint8 *current = slice;
1235 slice = *(gpointer*) (current + next_offset);
1236 if (G_UNLIKELY (allocator->config.debug_blocks) &&
1237 !smc_notify_free (current, mem_size))
1238 abort();
1239 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
1240 {
1241 thread_memory_swap_magazines (tmem, ix);
1242 if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix)))
1243 thread_memory_magazine2_unload (tmem, ix);
1244 }
1245 if (G_UNLIKELY (g_mem_gc_friendly))
1246 memset (current, 0, chunk_size);
1247 thread_memory_magazine2_free (tmem, ix, current);
1248 }
1249 }
1250 else if (acat == 2) /* allocate through slab allocator */
1251 {
1252 g_mutex_lock (&allocator->slab_mutex);
1253 while (slice)
1254 {
1255 guint8 *current = slice;
1256 slice = *(gpointer*) (current + next_offset);
1257 if (G_UNLIKELY (allocator->config.debug_blocks) &&
1258 !smc_notify_free (current, mem_size))
1259 abort();
1260 if (G_UNLIKELY (g_mem_gc_friendly))
1261 memset (current, 0, chunk_size);
1262 slab_allocator_free_chunk (chunk_size, current);
1263 }
1264 g_mutex_unlock (&allocator->slab_mutex);
1265 }
1266 else /* delegate to system malloc */
1267 while (slice)
1268 {
1269 guint8 *current = slice;
1270 slice = *(gpointer*) (current + next_offset);
1271 if (G_UNLIKELY (allocator->config.debug_blocks) &&
1272 !smc_notify_free (current, mem_size))
1273 abort();
1274 if (G_UNLIKELY (g_mem_gc_friendly))
1275 memset (current, 0, mem_size);
1276 g_free (current);
1277 }
1278 }
1279
1280 /* --- single page allocator --- */
1281 static void
allocator_slab_stack_push(Allocator * allocator,guint ix,SlabInfo * sinfo)1282 allocator_slab_stack_push (Allocator *allocator,
1283 guint ix,
1284 SlabInfo *sinfo)
1285 {
1286 /* insert slab at slab ring head */
1287 if (!allocator->slab_stack[ix])
1288 {
1289 sinfo->next = sinfo;
1290 sinfo->prev = sinfo;
1291 }
1292 else
1293 {
1294 SlabInfo *next = allocator->slab_stack[ix], *prev = next->prev;
1295 next->prev = sinfo;
1296 prev->next = sinfo;
1297 sinfo->next = next;
1298 sinfo->prev = prev;
1299 }
1300 allocator->slab_stack[ix] = sinfo;
1301 }
1302
1303 static gsize
allocator_aligned_page_size(Allocator * allocator,gsize n_bytes)1304 allocator_aligned_page_size (Allocator *allocator,
1305 gsize n_bytes)
1306 {
1307 gsize val = 1 << g_bit_storage (n_bytes - 1);
1308 val = MAX (val, allocator->min_page_size);
1309 return val;
1310 }
1311
1312 static void
allocator_add_slab(Allocator * allocator,guint ix,gsize chunk_size)1313 allocator_add_slab (Allocator *allocator,
1314 guint ix,
1315 gsize chunk_size)
1316 {
1317 ChunkLink *chunk;
1318 SlabInfo *sinfo;
1319 gsize addr, padding, n_chunks, color = 0;
1320 gsize page_size;
1321 int errsv;
1322 gpointer aligned_memory;
1323 guint8 *mem;
1324 guint i;
1325
1326 page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1327 /* allocate 1 page for the chunks and the slab */
1328 aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
1329 errsv = errno;
1330 mem = aligned_memory;
1331
1332 if (!mem)
1333 {
1334 const gchar *syserr = strerror (errsv);
1335 mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
1336 (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
1337 }
1338 /* mask page address */
1339 addr = ((gsize) mem / page_size) * page_size;
1340 /* assert alignment */
1341 mem_assert (aligned_memory == (gpointer) addr);
1342 /* basic slab info setup */
1343 sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE);
1344 sinfo->n_allocated = 0;
1345 sinfo->chunks = NULL;
1346 /* figure cache colorization */
1347 n_chunks = ((guint8*) sinfo - mem) / chunk_size;
1348 padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size;
1349 if (padding)
1350 {
1351 color = (allocator->color_accu * P2ALIGNMENT) % padding;
1352 allocator->color_accu += allocator->config.color_increment;
1353 }
1354 /* add chunks to free list */
1355 chunk = (ChunkLink*) (mem + color);
1356 sinfo->chunks = chunk;
1357 for (i = 0; i < n_chunks - 1; i++)
1358 {
1359 chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size);
1360 chunk = chunk->next;
1361 }
1362 chunk->next = NULL; /* last chunk */
1363 /* add slab to slab ring */
1364 allocator_slab_stack_push (allocator, ix, sinfo);
1365 }
1366
1367 static gpointer
slab_allocator_alloc_chunk(gsize chunk_size)1368 slab_allocator_alloc_chunk (gsize chunk_size)
1369 {
1370 ChunkLink *chunk;
1371 guint ix = SLAB_INDEX (allocator, chunk_size);
1372 /* ensure non-empty slab */
1373 if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks)
1374 allocator_add_slab (allocator, ix, chunk_size);
1375 /* allocate chunk */
1376 chunk = allocator->slab_stack[ix]->chunks;
1377 allocator->slab_stack[ix]->chunks = chunk->next;
1378 allocator->slab_stack[ix]->n_allocated++;
1379 /* rotate empty slabs */
1380 if (!allocator->slab_stack[ix]->chunks)
1381 allocator->slab_stack[ix] = allocator->slab_stack[ix]->next;
1382 return chunk;
1383 }
1384
1385 static void
slab_allocator_free_chunk(gsize chunk_size,gpointer mem)1386 slab_allocator_free_chunk (gsize chunk_size,
1387 gpointer mem)
1388 {
1389 ChunkLink *chunk;
1390 gboolean was_empty;
1391 guint ix = SLAB_INDEX (allocator, chunk_size);
1392 gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size));
1393 gsize addr = ((gsize) mem / page_size) * page_size;
1394 /* mask page address */
1395 guint8 *page = (guint8*) addr;
1396 SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
1397 /* assert valid chunk count */
1398 mem_assert (sinfo->n_allocated > 0);
1399 /* add chunk to free list */
1400 was_empty = sinfo->chunks == NULL;
1401 chunk = (ChunkLink*) mem;
1402 chunk->next = sinfo->chunks;
1403 sinfo->chunks = chunk;
1404 sinfo->n_allocated--;
1405 /* keep slab ring partially sorted, empty slabs at end */
1406 if (was_empty)
1407 {
1408 /* unlink slab */
1409 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1410 next->prev = prev;
1411 prev->next = next;
1412 if (allocator->slab_stack[ix] == sinfo)
1413 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1414 /* insert slab at head */
1415 allocator_slab_stack_push (allocator, ix, sinfo);
1416 }
1417 /* eagerly free complete unused slabs */
1418 if (!sinfo->n_allocated)
1419 {
1420 /* unlink slab */
1421 SlabInfo *next = sinfo->next, *prev = sinfo->prev;
1422 next->prev = prev;
1423 prev->next = next;
1424 if (allocator->slab_stack[ix] == sinfo)
1425 allocator->slab_stack[ix] = next == sinfo ? NULL : next;
1426 /* free slab */
1427 allocator_memfree (page_size, page);
1428 }
1429 }
1430
1431 /* --- memalign implementation --- */
1432 #ifdef HAVE_MALLOC_H
1433 #include <malloc.h> /* memalign() */
1434 #endif
1435
1436 /* from config.h:
1437 * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
1438 * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
1439 * define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
1440 * if none is provided, we implement malloc(3)-based alloc-only page alignment
1441 */
1442
1443 #if !(HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
1444 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1445 static GTrashStack *compat_valloc_trash = NULL;
1446 G_GNUC_END_IGNORE_DEPRECATIONS
1447 #endif
1448
1449 static gpointer
allocator_memalign(gsize alignment,gsize memsize)1450 allocator_memalign (gsize alignment,
1451 gsize memsize)
1452 {
1453 gpointer aligned_memory = NULL;
1454 gint err = ENOMEM;
1455 #if HAVE_POSIX_MEMALIGN
1456 err = posix_memalign (&aligned_memory, alignment, memsize);
1457 #elif HAVE_MEMALIGN
1458 errno = 0;
1459 aligned_memory = memalign (alignment, memsize);
1460 err = errno;
1461 #elif HAVE_VALLOC
1462 errno = 0;
1463 aligned_memory = valloc (memsize);
1464 err = errno;
1465 #else
1466 /* simplistic non-freeing page allocator */
1467 mem_assert (alignment == sys_page_size);
1468 mem_assert (memsize <= sys_page_size);
1469 if (!compat_valloc_trash)
1470 {
1471 const guint n_pages = 16;
1472 guint8 *mem = malloc (n_pages * sys_page_size);
1473 err = errno;
1474 if (mem)
1475 {
1476 gint i = n_pages;
1477 guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
1478 if (amem != mem)
1479 i--; /* mem wasn't page aligned */
1480 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1481 while (--i >= 0)
1482 g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
1483 G_GNUC_END_IGNORE_DEPRECATIONS
1484 }
1485 }
1486 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1487 aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
1488 G_GNUC_END_IGNORE_DEPRECATIONS
1489 #endif
1490 if (!aligned_memory)
1491 errno = err;
1492 return aligned_memory;
1493 }
1494
1495 static void
allocator_memfree(gsize memsize,gpointer mem)1496 allocator_memfree (gsize memsize,
1497 gpointer mem)
1498 {
1499 #if HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC
1500 free (mem);
1501 #else
1502 mem_assert (memsize <= sys_page_size);
1503 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
1504 g_trash_stack_push (&compat_valloc_trash, mem);
1505 G_GNUC_END_IGNORE_DEPRECATIONS
1506 #endif
1507 }
1508
1509 static void
mem_error(const char * format,...)1510 mem_error (const char *format,
1511 ...)
1512 {
1513 const char *pname;
1514 va_list args;
1515 /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */
1516 fputs ("\n***MEMORY-ERROR***: ", stderr);
1517 pname = g_get_prgname();
1518 g_fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid());
1519 va_start (args, format);
1520 g_vfprintf (stderr, format, args);
1521 va_end (args);
1522 fputs ("\n", stderr);
1523 abort();
1524 _exit (1);
1525 }
1526
1527 /* --- g-slice memory checker tree --- */
1528 typedef size_t SmcKType; /* key type */
1529 typedef size_t SmcVType; /* value type */
1530 typedef struct {
1531 SmcKType key;
1532 SmcVType value;
1533 } SmcEntry;
1534 static void smc_tree_insert (SmcKType key,
1535 SmcVType value);
1536 static gboolean smc_tree_lookup (SmcKType key,
1537 SmcVType *value_p);
1538 static gboolean smc_tree_remove (SmcKType key);
1539
1540
1541 /* --- g-slice memory checker implementation --- */
1542 static void
smc_notify_alloc(void * pointer,size_t size)1543 smc_notify_alloc (void *pointer,
1544 size_t size)
1545 {
1546 size_t address = (size_t) pointer;
1547 if (pointer)
1548 smc_tree_insert (address, size);
1549 }
1550
1551 #if 0
1552 static void
1553 smc_notify_ignore (void *pointer)
1554 {
1555 size_t address = (size_t) pointer;
1556 if (pointer)
1557 smc_tree_remove (address);
1558 }
1559 #endif
1560
1561 static int
smc_notify_free(void * pointer,size_t size)1562 smc_notify_free (void *pointer,
1563 size_t size)
1564 {
1565 size_t address = (size_t) pointer;
1566 SmcVType real_size;
1567 gboolean found_one;
1568
1569 if (!pointer)
1570 return 1; /* ignore */
1571 found_one = smc_tree_lookup (address, &real_size);
1572 if (!found_one)
1573 {
1574 g_fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1575 return 0;
1576 }
1577 if (real_size != size && (real_size || size))
1578 {
1579 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);
1580 return 0;
1581 }
1582 if (!smc_tree_remove (address))
1583 {
1584 g_fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size);
1585 return 0;
1586 }
1587 return 1; /* all fine */
1588 }
1589
1590 /* --- g-slice memory checker tree implementation --- */
1591 #define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */
1592 #define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */
1593 #define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key address space per trunk, should distribute uniformly across BRANCH_COUNT */
1594 #define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */
1595 #define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT)
1596
1597 typedef struct {
1598 SmcEntry *entries;
1599 unsigned int n_entries;
1600 } SmcBranch;
1601
1602 static SmcBranch **smc_tree_root = NULL;
1603
1604 static void
smc_tree_abort(int errval)1605 smc_tree_abort (int errval)
1606 {
1607 const char *syserr = strerror (errval);
1608 mem_error ("MemChecker: failure in debugging tree: %s", syserr);
1609 }
1610
1611 static inline SmcEntry*
smc_tree_branch_grow_L(SmcBranch * branch,unsigned int index)1612 smc_tree_branch_grow_L (SmcBranch *branch,
1613 unsigned int index)
1614 {
1615 unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]);
1616 unsigned int new_size = old_size + sizeof (branch->entries[0]);
1617 SmcEntry *entry;
1618 mem_assert (index <= branch->n_entries);
1619 branch->entries = (SmcEntry*) realloc (branch->entries, new_size);
1620 if (!branch->entries)
1621 smc_tree_abort (errno);
1622 entry = branch->entries + index;
1623 memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0]));
1624 branch->n_entries += 1;
1625 return entry;
1626 }
1627
1628 static inline SmcEntry*
smc_tree_branch_lookup_nearest_L(SmcBranch * branch,SmcKType key)1629 smc_tree_branch_lookup_nearest_L (SmcBranch *branch,
1630 SmcKType key)
1631 {
1632 unsigned int n_nodes = branch->n_entries, offs = 0;
1633 SmcEntry *check = branch->entries;
1634 int cmp = 0;
1635 while (offs < n_nodes)
1636 {
1637 unsigned int i = (offs + n_nodes) >> 1;
1638 check = branch->entries + i;
1639 cmp = key < check->key ? -1 : key != check->key;
1640 if (cmp == 0)
1641 return check; /* return exact match */
1642 else if (cmp < 0)
1643 n_nodes = i;
1644 else /* (cmp > 0) */
1645 offs = i + 1;
1646 }
1647 /* check points at last mismatch, cmp > 0 indicates greater key */
1648 return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */
1649 }
1650
1651 static void
smc_tree_insert(SmcKType key,SmcVType value)1652 smc_tree_insert (SmcKType key,
1653 SmcVType value)
1654 {
1655 unsigned int ix0, ix1;
1656 SmcEntry *entry;
1657
1658 g_mutex_lock (&smc_tree_mutex);
1659 ix0 = SMC_TRUNK_HASH (key);
1660 ix1 = SMC_BRANCH_HASH (key);
1661 if (!smc_tree_root)
1662 {
1663 smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0]));
1664 if (!smc_tree_root)
1665 smc_tree_abort (errno);
1666 }
1667 if (!smc_tree_root[ix0])
1668 {
1669 smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0]));
1670 if (!smc_tree_root[ix0])
1671 smc_tree_abort (errno);
1672 }
1673 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1674 if (!entry || /* need create */
1675 entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */
1676 entry->key != key) /* need insert */
1677 entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries);
1678 entry->key = key;
1679 entry->value = value;
1680 g_mutex_unlock (&smc_tree_mutex);
1681 }
1682
1683 static gboolean
smc_tree_lookup(SmcKType key,SmcVType * value_p)1684 smc_tree_lookup (SmcKType key,
1685 SmcVType *value_p)
1686 {
1687 SmcEntry *entry = NULL;
1688 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1689 gboolean found_one = FALSE;
1690 *value_p = 0;
1691 g_mutex_lock (&smc_tree_mutex);
1692 if (smc_tree_root && smc_tree_root[ix0])
1693 {
1694 entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1695 if (entry &&
1696 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1697 entry->key == key)
1698 {
1699 found_one = TRUE;
1700 *value_p = entry->value;
1701 }
1702 }
1703 g_mutex_unlock (&smc_tree_mutex);
1704 return found_one;
1705 }
1706
1707 static gboolean
smc_tree_remove(SmcKType key)1708 smc_tree_remove (SmcKType key)
1709 {
1710 unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key);
1711 gboolean found_one = FALSE;
1712 g_mutex_lock (&smc_tree_mutex);
1713 if (smc_tree_root && smc_tree_root[ix0])
1714 {
1715 SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key);
1716 if (entry &&
1717 entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries &&
1718 entry->key == key)
1719 {
1720 unsigned int i = entry - smc_tree_root[ix0][ix1].entries;
1721 smc_tree_root[ix0][ix1].n_entries -= 1;
1722 memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0]));
1723 if (!smc_tree_root[ix0][ix1].n_entries)
1724 {
1725 /* avoid useless pressure on the memory system */
1726 free (smc_tree_root[ix0][ix1].entries);
1727 smc_tree_root[ix0][ix1].entries = NULL;
1728 }
1729 found_one = TRUE;
1730 }
1731 }
1732 g_mutex_unlock (&smc_tree_mutex);
1733 return found_one;
1734 }
1735
1736 #ifdef G_ENABLE_DEBUG
1737 void
g_slice_debug_tree_statistics(void)1738 g_slice_debug_tree_statistics (void)
1739 {
1740 g_mutex_lock (&smc_tree_mutex);
1741 if (smc_tree_root)
1742 {
1743 unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u;
1744 double tf, bf;
1745 for (i = 0; i < SMC_TRUNK_COUNT; i++)
1746 if (smc_tree_root[i])
1747 {
1748 t++;
1749 for (j = 0; j < SMC_BRANCH_COUNT; j++)
1750 if (smc_tree_root[i][j].n_entries)
1751 {
1752 b++;
1753 su += smc_tree_root[i][j].n_entries;
1754 en = MIN (en, smc_tree_root[i][j].n_entries);
1755 ex = MAX (ex, smc_tree_root[i][j].n_entries);
1756 }
1757 else if (smc_tree_root[i][j].entries)
1758 o++; /* formerly used, now empty */
1759 }
1760 en = b ? en : 0;
1761 tf = MAX (t, 1.0); /* max(1) to be a valid divisor */
1762 bf = MAX (b, 1.0); /* max(1) to be a valid divisor */
1763 g_fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o);
1764 g_fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n",
1765 b / tf,
1766 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT));
1767 g_fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n",
1768 su / bf, en, ex);
1769 }
1770 else
1771 g_fprintf (stderr, "GSlice: MemChecker: root=NULL\n");
1772 g_mutex_unlock (&smc_tree_mutex);
1773
1774 /* sample statistics (beast + GSLice + 24h scripted core & GUI activity):
1775 * PID %CPU %MEM VSZ RSS COMMAND
1776 * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse
1777 * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages
1778 * 114017 103714 2354 344 0 108676 0
1779 * $ cat /proc/8887/status
1780 * Name: beast-0.7.1
1781 * VmSize: 456068 kB
1782 * VmLck: 0 kB
1783 * VmRSS: 414856 kB
1784 * VmData: 434620 kB
1785 * VmStk: 84 kB
1786 * VmExe: 1376 kB
1787 * VmLib: 13036 kB
1788 * VmPTE: 456 kB
1789 * Threads: 3
1790 * (gdb) print g_slice_debug_tree_statistics ()
1791 * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches
1792 * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization
1793 * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum
1794 */
1795 }
1796 #endif /* G_ENABLE_DEBUG */
1797