diff --git a/NEWS b/NEWS index 2decbc7dd..30ee5cad3 100644 --- a/NEWS +++ b/NEWS @@ -1,3 +1,10 @@ +Overview of changes in GLib 2.75.3, UNRELEASED +============================================== + +* Drop the implementation of GSlice, and make the API use the system `malloc()` + internally (#1079) (based on investigation work by multiple people) + + Overview of changes in GLib 2.75.2, 2023-01-06 ============================================== diff --git a/docs/reference/glib/running.xml b/docs/reference/glib/running.xml index 80a8da097..dbf22ad1e 100644 --- a/docs/reference/glib/running.xml +++ b/docs/reference/glib/running.xml @@ -165,53 +165,10 @@ How to run and debug your GLib application <envar>G_SLICE</envar> - This environment variable allows reconfiguration of the GSlice - memory allocator. - - - always-malloc - This will cause all slices allocated through - g_slice_alloc() and released by g_slice_free1() to be actually - allocated via direct calls to g_malloc() and g_free(). - This is most useful for memory checkers and similar programs that - use Boehm GC alike algorithms to produce more accurate results. - It can also be in conjunction with debugging features of the system's - malloc() implementation such as glibc's MALLOC_CHECK_=2 to debug - erroneous slice allocation code, although - debug-blocks is usually a better suited debugging - tool. - - - - debug-blocks - Using this option (present since GLib 2.13) engages - extra code which performs sanity checks on the released memory - slices. Invalid slice addresses or slice sizes will be reported and - lead to a program halt. This option is for debugging scenarios. - In particular, client packages sporting their own test suite should - always enable this option when running tests. - Global slice validation is ensured by storing size and address - information for each allocated chunk, and maintaining a global - hash table of that data. That way, multi-thread scalability is - given up, and memory consumption is increased. However, the - resulting code usually performs acceptably well, possibly better - than with comparable memory checking carried out using external - tools. - An example of a memory corruption scenario that cannot be - reproduced with G_SLICE=always-malloc, but will - be caught by G_SLICE=debug-blocks is as follows: - - /* void* gives up type-safety */ - void *slist = g_slist_alloc (); - - /* corruption: sizeof (GSList) != sizeof (GList) */ - g_list_free (slist); - - - - - The special value all can be used to turn on all options. - The special value help can be used to print all available options. + This environment variable allowed reconfiguration of the GSlice + memory allocator. Since GLib 2.76, GSlice uses the system + malloc() implementation internally, so this variable is + ignored. diff --git a/glib/gslice.c b/glib/gslice.c index 56f217d32..cd98220e4 100644 --- a/glib/gslice.c +++ b/glib/gslice.c @@ -21,75 +21,33 @@ #include "config.h" #include "glibconfig.h" -#if defined(HAVE_POSIX_MEMALIGN) && !defined(_XOPEN_SOURCE) -#define _XOPEN_SOURCE 600 /* posix_memalign() */ -#endif -#include /* posix_memalign() */ +#include #include -#include - -#ifdef G_OS_UNIX -#include /* sysconf() */ -#endif -#ifdef G_OS_WIN32 -#include -#include -#endif - -#include /* fputs */ #include "gslice.h" -#include "gmain.h" #include "gmem.h" /* gslice.h */ -#include "gstrfuncs.h" -#include "gutils.h" -#include "gtrashstack.h" -#include "gtestutils.h" -#include "gthread.h" -#include "gthreadprivate.h" #include "glib_trace.h" #include "gprintf.h" -#include "gvalgrind.h" - /** * SECTION:memory_slices * @title: Memory Slices * @short_description: efficient way to allocate groups of equal-sized * chunks of memory * - * Memory slices provide a space-efficient and multi-processing scalable - * way to allocate equal-sized pieces of memory, just like the original - * #GMemChunks (from GLib 2.8), while avoiding their excessive - * memory-waste, scalability and performance problems. + * GSlice was a space-efficient and multi-processing scalable way to allocate + * equal sized pieces of memory. Since GLib 2.76, its implementation has been + * removed and it calls g_malloc() and g_free(), because the performance of the + * system-default allocators has improved on all platforms since GSlice was + * written. * - * To achieve these goals, the slice allocator uses a sophisticated, - * layered design that has been inspired by Bonwick's slab allocator - * ([Bonwick94](http://citeseer.ist.psu.edu/bonwick94slab.html) - * Jeff Bonwick, The slab allocator: An object-caching kernel - * memory allocator. USENIX 1994, and - * [Bonwick01](http://citeseer.ist.psu.edu/bonwick01magazines.html) - * Bonwick and Jonathan Adams, Magazines and vmem: Extending the - * slab allocator to many cpu's and arbitrary resources. USENIX 2001) + * The GSlice APIs have not been deprecated, as they are widely in use and doing + * so would be very disruptive for little benefit. * - * It uses posix_memalign() to optimize allocations of many equally-sized - * chunks, and has per-thread free lists (the so-called magazine layer) - * to quickly satisfy allocation requests of already known structure sizes. - * This is accompanied by extra caching logic to keep freed memory around - * for some time before returning it to the system. Memory that is unused - * due to alignment constraints is used for cache colorization (random - * distribution of chunk addresses) to improve CPU cache utilization. The - * caching layer of the slice allocator adapts itself to high lock contention - * to improve scalability. - * - * The slice allocator can allocate blocks as small as two pointers, and - * unlike malloc(), it does not reserve extra space per block. For large block - * sizes, g_slice_new() and g_slice_alloc() will automatically delegate to the - * system malloc() implementation. For newly written code it is recommended - * to use the new `g_slice` API instead of g_malloc() and - * friends, as long as objects are not resized during their lifetime and the - * object size used at allocation time is still available when freeing. + * New code should be written using g_new()/g_malloc() and g_free(). There is no + * particular benefit in porting existing code away from + * g_slice_new()/g_slice_free() unless it’s being rewritten anyway. * * Here is an example for using the slice allocator: * |[ @@ -132,209 +90,19 @@ * ]| */ -/* the GSlice allocator is split up into 4 layers, roughly modelled after the slab - * allocator and magazine extensions as outlined in: - * + [Bonwick94] Jeff Bonwick, The slab allocator: An object-caching kernel - * memory allocator. USENIX 1994, http://citeseer.ist.psu.edu/bonwick94slab.html - * + [Bonwick01] Bonwick and Jonathan Adams, Magazines and vmem: Extending the - * slab allocator to many cpu's and arbitrary resources. - * USENIX 2001, http://citeseer.ist.psu.edu/bonwick01magazines.html - * the layers are: - * - the thread magazines. for each (aligned) chunk size, a magazine (a list) - * of recently freed and soon to be allocated chunks is maintained per thread. - * this way, most alloc/free requests can be quickly satisfied from per-thread - * free lists which only require one g_private_get() call to retrieve the - * thread handle. - * - the magazine cache. allocating and freeing chunks to/from threads only - * occurs at magazine sizes from a global depot of magazines. the depot - * maintaines a 15 second working set of allocated magazines, so full - * magazines are not allocated and released too often. - * the chunk size dependent magazine sizes automatically adapt (within limits, - * see [3]) to lock contention to properly scale performance across a variety - * of SMP systems. - * - the slab allocator. this allocator allocates slabs (blocks of memory) close - * to the system page size or multiples thereof which have to be page aligned. - * the blocks are divided into smaller chunks which are used to satisfy - * allocations from the upper layers. the space provided by the reminder of - * the chunk size division is used for cache colorization (random distribution - * of chunk addresses) to improve processor cache utilization. multiple slabs - * with the same chunk size are kept in a partially sorted ring to allow O(1) - * freeing and allocation of chunks (as long as the allocation of an entirely - * new slab can be avoided). - * - the page allocator. on most modern systems, posix_memalign(3) or - * memalign(3) should be available, so this is used to allocate blocks with - * system page size based alignments and sizes or multiples thereof. - * if no memalign variant is provided, valloc() is used instead and - * block sizes are limited to the system page size (no multiples thereof). - * as a fallback, on system without even valloc(), a malloc(3)-based page - * allocator with alloc-only behaviour is used. - * - * NOTES: - * [1] some systems memalign(3) implementations may rely on boundary tagging for - * the handed out memory chunks. to avoid excessive page-wise fragmentation, - * we reserve 2 * sizeof (void*) per block size for the systems memalign(3), - * specified in NATIVE_MALLOC_PADDING. - * [2] using the slab allocator alone already provides for a fast and efficient - * allocator, it doesn't properly scale beyond single-threaded uses though. - * also, the slab allocator implements eager free(3)-ing, i.e. does not - * provide any form of caching or working set maintenance. so if used alone, - * it's vulnerable to trashing for sequences of balanced (alloc, free) pairs - * at certain thresholds. - * [3] magazine sizes are bound by an implementation specific minimum size and - * a chunk size specific maximum to limit magazine storage sizes to roughly - * 16KB. - * [4] allocating ca. 8 chunks per block/page keeps a good balance between - * external and internal fragmentation (<= 12.5%). [Bonwick94] - */ - -/* --- macros and constants --- */ -#define LARGEALIGNMENT (256) -#define P2ALIGNMENT (2 * sizeof (gsize)) /* fits 2 pointers (assumed to be 2 * GLIB_SIZEOF_SIZE_T below) */ -#define ALIGN(size, base) ((base) * (gsize) (((size) + (base) - 1) / (base))) -#define NATIVE_MALLOC_PADDING P2ALIGNMENT /* per-page padding left for native malloc(3) see [1] */ -#define SLAB_INFO_SIZE P2ALIGN (sizeof (SlabInfo) + NATIVE_MALLOC_PADDING) -#define MAX_MAGAZINE_SIZE (256) /* see [3] and allocator_get_magazine_threshold() for this */ -#define MIN_MAGAZINE_SIZE (4) -#define MAX_STAMP_COUNTER (7) /* distributes the load of gettimeofday() */ -#define MAX_SLAB_CHUNK_SIZE(al) (((al)->max_page_size - SLAB_INFO_SIZE) / 8) /* we want at last 8 chunks per page, see [4] */ -#define MAX_SLAB_INDEX(al) (SLAB_INDEX (al, MAX_SLAB_CHUNK_SIZE (al)) + 1) -#define SLAB_INDEX(al, asize) ((asize) / P2ALIGNMENT - 1) /* asize must be P2ALIGNMENT aligned */ -#define SLAB_CHUNK_SIZE(al, ix) (((ix) + 1) * P2ALIGNMENT) -#define SLAB_BPAGE_SIZE(al,csz) (8 * (csz) + SLAB_INFO_SIZE) - -/* optimized version of ALIGN (size, P2ALIGNMENT) */ -#if GLIB_SIZEOF_SIZE_T * 2 == 8 /* P2ALIGNMENT */ -#define P2ALIGN(size) (((size) + 0x7) & ~(gsize) 0x7) -#elif GLIB_SIZEOF_SIZE_T * 2 == 16 /* P2ALIGNMENT */ -#define P2ALIGN(size) (((size) + 0xf) & ~(gsize) 0xf) -#else -#define P2ALIGN(size) ALIGN (size, P2ALIGNMENT) -#endif - -/* special helpers to avoid gmessage.c dependency */ -G_NORETURN static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2) G_ANALYZER_NORETURN; -#define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0) - -/* --- structures --- */ -typedef struct _ChunkLink ChunkLink; -typedef struct _SlabInfo SlabInfo; -typedef struct _CachedMagazine CachedMagazine; -struct _ChunkLink { - ChunkLink *next; - ChunkLink *data; -}; -struct _SlabInfo { - ChunkLink *chunks; - guint n_allocated; - SlabInfo *next, *prev; -}; -typedef struct { - ChunkLink *chunks; - gsize count; /* approximative chunks list length */ -} Magazine; -typedef struct { - Magazine *magazine1; /* array of MAX_SLAB_INDEX (allocator) */ - Magazine *magazine2; /* array of MAX_SLAB_INDEX (allocator) */ -} ThreadMemory; -typedef struct { - gboolean always_malloc; - gboolean bypass_magazines; - gboolean debug_blocks; - gsize working_set_msecs; - guint color_increment; -} SliceConfig; -typedef struct { - /* const after initialization */ - gsize min_page_size, max_page_size; - SliceConfig config; - gsize max_slab_chunk_size_for_magazine_cache; - /* magazine cache */ - GMutex magazine_mutex; - ChunkLink **magazines; /* array of MAX_SLAB_INDEX (allocator) */ - guint *contention_counters; /* array of MAX_SLAB_INDEX (allocator) */ - gint mutex_counter; - guint stamp_counter; - guint last_stamp; - /* slab allocator */ - GMutex slab_mutex; - SlabInfo **slab_stack; /* array of MAX_SLAB_INDEX (allocator) */ - guint color_accu; -} Allocator; - -/* --- g-slice prototypes --- */ -static gpointer slab_allocator_alloc_chunk (gsize chunk_size); -static void slab_allocator_free_chunk (gsize chunk_size, - gpointer mem); -static void private_thread_memory_cleanup (gpointer data); -static gpointer allocator_memalign (gsize alignment, - gsize memsize); -static void allocator_memfree (gsize memsize, - gpointer mem); -static inline void magazine_cache_update_stamp (void); -static inline gsize allocator_get_magazine_threshold (Allocator *allocator, - guint ix); - -/* --- g-slice memory checker --- */ -static void smc_notify_alloc (void *pointer, - size_t size); -static int smc_notify_free (void *pointer, - size_t size); - -/* --- variables --- */ -static GPrivate private_thread_memory = G_PRIVATE_INIT (private_thread_memory_cleanup); -static gsize sys_page_size = 0; -static Allocator allocator[1] = { { 0, }, }; -static SliceConfig slice_config = { - FALSE, /* always_malloc */ - FALSE, /* bypass_magazines */ - FALSE, /* debug_blocks */ - 15 * 1000, /* working_set_msecs */ - 1, /* color increment, alt: 0x7fffffff */ -}; -static GMutex smc_tree_mutex; /* mutex for G_SLICE=debug-blocks */ - /* --- auxiliary functions --- */ void g_slice_set_config (GSliceConfig ckey, gint64 value) { - g_return_if_fail (sys_page_size == 0); - switch (ckey) - { - case G_SLICE_CONFIG_ALWAYS_MALLOC: - slice_config.always_malloc = value != 0; - break; - case G_SLICE_CONFIG_BYPASS_MAGAZINES: - slice_config.bypass_magazines = value != 0; - break; - case G_SLICE_CONFIG_WORKING_SET_MSECS: - slice_config.working_set_msecs = value; - break; - case G_SLICE_CONFIG_COLOR_INCREMENT: - slice_config.color_increment = value; - break; - default: ; - } + /* deprecated, no implementation */ } gint64 g_slice_get_config (GSliceConfig ckey) { - switch (ckey) - { - case G_SLICE_CONFIG_ALWAYS_MALLOC: - return slice_config.always_malloc; - case G_SLICE_CONFIG_BYPASS_MAGAZINES: - return slice_config.bypass_magazines; - case G_SLICE_CONFIG_WORKING_SET_MSECS: - return slice_config.working_set_msecs; - case G_SLICE_CONFIG_CHUNK_SIZES: - return MAX_SLAB_INDEX (allocator); - case G_SLICE_CONFIG_COLOR_INCREMENT: - return slice_config.color_increment; - default: - return 0; - } + /* deprecated, no implementation */ + return 0; } gint64* @@ -342,566 +110,8 @@ g_slice_get_config_state (GSliceConfig ckey, gint64 address, guint *n_values) { - guint i = 0; - g_return_val_if_fail (n_values != NULL, NULL); - *n_values = 0; - switch (ckey) - { - gint64 array[64]; - case G_SLICE_CONFIG_CONTENTION_COUNTER: - array[i++] = SLAB_CHUNK_SIZE (allocator, address); - array[i++] = allocator->contention_counters[address]; - array[i++] = allocator_get_magazine_threshold (allocator, address); - *n_values = i; - return g_memdup2 (array, sizeof (array[0]) * *n_values); - default: - return NULL; - } -} - -static void -slice_config_init (SliceConfig *config) -{ - const gchar *val; - gchar *val_allocated = NULL; - - *config = slice_config; - - /* Note that the empty string (`G_SLICE=""`) is treated differently from the - * envvar being unset. In the latter case, we also check whether running under - * valgrind. */ -#ifndef G_OS_WIN32 - val = g_getenv ("G_SLICE"); -#else - /* The win32 implementation of g_getenv() has to do UTF-8 ↔ UTF-16 conversions - * which use the slice allocator, leading to deadlock. Use a simple in-place - * implementation here instead. - * - * Ignore references to other environment variables: only support values which - * are a combination of always-malloc and debug-blocks. */ - { - - wchar_t wvalue[128]; /* at least big enough for `always-malloc,debug-blocks` */ - gsize len; - - len = GetEnvironmentVariableW (L"G_SLICE", wvalue, G_N_ELEMENTS (wvalue)); - - if (len == 0) - { - if (GetLastError () == ERROR_ENVVAR_NOT_FOUND) - val = NULL; - else - val = ""; - } - else if (len >= G_N_ELEMENTS (wvalue)) - { - /* @wvalue isn’t big enough. Give up. */ - g_warning ("Unsupported G_SLICE value"); - val = NULL; - } - else - { - /* it’s safe to use g_utf16_to_utf8() here as it only allocates using - * malloc() rather than GSlice */ - val = val_allocated = g_utf16_to_utf8 (wvalue, -1, NULL, NULL, NULL); - } - - } -#endif /* G_OS_WIN32 */ - - if (val != NULL) - { - gint flags; - const GDebugKey keys[] = { - { "always-malloc", 1 << 0 }, - { "debug-blocks", 1 << 1 }, - }; - - flags = g_parse_debug_string (val, keys, G_N_ELEMENTS (keys)); - if (flags & (1 << 0)) - config->always_malloc = TRUE; - if (flags & (1 << 1)) - config->debug_blocks = TRUE; - } - else - { - /* G_SLICE was not specified, so check if valgrind is running and - * disable ourselves if it is. - * - * This way it's possible to force gslice to be enabled under - * valgrind just by setting G_SLICE to the empty string. - */ -#ifdef ENABLE_VALGRIND - if (RUNNING_ON_VALGRIND) - config->always_malloc = TRUE; -#endif - } - - g_free (val_allocated); -} - -static void -g_slice_init_nomessage (void) -{ - /* we may not use g_error() or friends here */ - mem_assert (sys_page_size == 0); - mem_assert (MIN_MAGAZINE_SIZE >= 4); - -#ifdef G_OS_WIN32 - { - SYSTEM_INFO system_info; - GetSystemInfo (&system_info); - sys_page_size = system_info.dwPageSize; - } -#else - sys_page_size = sysconf (_SC_PAGESIZE); /* = sysconf (_SC_PAGE_SIZE); = getpagesize(); */ -#endif - mem_assert (sys_page_size >= 2 * LARGEALIGNMENT); - mem_assert ((sys_page_size & (sys_page_size - 1)) == 0); - slice_config_init (&allocator->config); - allocator->min_page_size = sys_page_size; -#if HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN - /* allow allocation of pages up to 8KB (with 8KB alignment). - * this is useful because many medium to large sized structures - * fit less than 8 times (see [4]) into 4KB pages. - * we allow very small page sizes here, to reduce wastage in - * threads if only small allocations are required (this does - * bear the risk of increasing allocation times and fragmentation - * though). - */ - allocator->min_page_size = MAX (allocator->min_page_size, 4096); - allocator->max_page_size = MAX (allocator->min_page_size, 8192); - allocator->min_page_size = MIN (allocator->min_page_size, 128); -#else - /* we can only align to system page size */ - allocator->max_page_size = sys_page_size; -#endif - if (allocator->config.always_malloc) - { - allocator->contention_counters = NULL; - allocator->magazines = NULL; - allocator->slab_stack = NULL; - } - else - { - allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator)); - allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator)); - allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator)); - } - - allocator->mutex_counter = 0; - allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */ - allocator->last_stamp = 0; - allocator->color_accu = 0; - magazine_cache_update_stamp(); - /* values cached for performance reasons */ - allocator->max_slab_chunk_size_for_magazine_cache = MAX_SLAB_CHUNK_SIZE (allocator); - if (allocator->config.always_malloc || allocator->config.bypass_magazines) - allocator->max_slab_chunk_size_for_magazine_cache = 0; /* non-optimized cases */ -} - -static inline guint -allocator_categorize (gsize aligned_chunk_size) -{ - /* speed up the likely path */ - if (G_LIKELY (aligned_chunk_size && aligned_chunk_size <= allocator->max_slab_chunk_size_for_magazine_cache)) - return 1; /* use magazine cache */ - - if (!allocator->config.always_malloc && - aligned_chunk_size && - aligned_chunk_size <= MAX_SLAB_CHUNK_SIZE (allocator)) - { - if (allocator->config.bypass_magazines) - return 2; /* use slab allocator, see [2] */ - return 1; /* use magazine cache */ - } - return 0; /* use malloc() */ -} - -static inline void -g_mutex_lock_a (GMutex *mutex, - guint *contention_counter) -{ - gboolean contention = FALSE; - if (!g_mutex_trylock (mutex)) - { - g_mutex_lock (mutex); - contention = TRUE; - } - if (contention) - { - allocator->mutex_counter++; - if (allocator->mutex_counter >= 1) /* quickly adapt to contention */ - { - allocator->mutex_counter = 0; - *contention_counter = MIN (*contention_counter + 1, MAX_MAGAZINE_SIZE); - } - } - else /* !contention */ - { - allocator->mutex_counter--; - if (allocator->mutex_counter < -11) /* moderately recover magazine sizes */ - { - allocator->mutex_counter = 0; - *contention_counter = MAX (*contention_counter, 1) - 1; - } - } -} - -static inline ThreadMemory* -thread_memory_from_self (void) -{ - ThreadMemory *tmem = g_private_get (&private_thread_memory); - if (G_UNLIKELY (!tmem)) - { - static GMutex init_mutex; - guint n_magazines; - - g_mutex_lock (&init_mutex); - if G_UNLIKELY (sys_page_size == 0) - g_slice_init_nomessage (); - g_mutex_unlock (&init_mutex); - - n_magazines = MAX_SLAB_INDEX (allocator); - tmem = g_private_set_alloc0 (&private_thread_memory, sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines); - tmem->magazine1 = (Magazine*) (tmem + 1); - tmem->magazine2 = &tmem->magazine1[n_magazines]; - } - return tmem; -} - -static inline ChunkLink* -magazine_chain_pop_head (ChunkLink **magazine_chunks) -{ - /* magazine chains are linked via ChunkLink->next. - * each ChunkLink->data of the toplevel chain may point to a subchain, - * linked via ChunkLink->next. ChunkLink->data of the subchains just - * contains uninitialized junk. - */ - ChunkLink *chunk = (*magazine_chunks)->data; - if (G_UNLIKELY (chunk)) - { - /* allocating from freed list */ - (*magazine_chunks)->data = chunk->next; - } - else - { - chunk = *magazine_chunks; - *magazine_chunks = chunk->next; - } - return chunk; -} - -#if 0 /* useful for debugging */ -static guint -magazine_count (ChunkLink *head) -{ - guint count = 0; - if (!head) - return 0; - while (head) - { - ChunkLink *child = head->data; - count += 1; - for (child = head->data; child; child = child->next) - count += 1; - head = head->next; - } - return count; -} -#endif - -static inline gsize -allocator_get_magazine_threshold (Allocator *local_allocator, - guint ix) -{ - /* the magazine size calculated here has a lower bound of MIN_MAGAZINE_SIZE, - * which is required by the implementation. also, for moderately sized chunks - * (say >= 64 bytes), magazine sizes shouldn't be much smaller then the number - * of chunks available per page/2 to avoid excessive traffic in the magazine - * cache for small to medium sized structures. - * the upper bound of the magazine size is effectively provided by - * MAX_MAGAZINE_SIZE. for larger chunks, this number is scaled down so that - * the content of a single magazine doesn't exceed ca. 16KB. - */ - gsize chunk_size = SLAB_CHUNK_SIZE (local_allocator, ix); - guint threshold = MAX (MIN_MAGAZINE_SIZE, local_allocator->max_page_size / MAX (5 * chunk_size, 5 * 32)); - guint contention_counter = local_allocator->contention_counters[ix]; - if (G_UNLIKELY (contention_counter)) /* single CPU bias */ - { - /* adapt contention counter thresholds to chunk sizes */ - contention_counter = contention_counter * 64 / chunk_size; - threshold = MAX (threshold, contention_counter); - } - return threshold; -} - -/* --- magazine cache --- */ -static inline void -magazine_cache_update_stamp (void) -{ - if (allocator->stamp_counter >= MAX_STAMP_COUNTER) - { - gint64 now_us = g_get_real_time (); - allocator->last_stamp = now_us / 1000; /* milli seconds */ - allocator->stamp_counter = 0; - } - else - allocator->stamp_counter++; -} - -static inline ChunkLink* -magazine_chain_prepare_fields (ChunkLink *magazine_chunks) -{ - ChunkLink *chunk1; - ChunkLink *chunk2; - ChunkLink *chunk3; - ChunkLink *chunk4; - /* checked upon initialization: mem_assert (MIN_MAGAZINE_SIZE >= 4); */ - /* ensure a magazine with at least 4 unused data pointers */ - chunk1 = magazine_chain_pop_head (&magazine_chunks); - chunk2 = magazine_chain_pop_head (&magazine_chunks); - chunk3 = magazine_chain_pop_head (&magazine_chunks); - chunk4 = magazine_chain_pop_head (&magazine_chunks); - chunk4->next = magazine_chunks; - chunk3->next = chunk4; - chunk2->next = chunk3; - chunk1->next = chunk2; - return chunk1; -} - -/* access the first 3 fields of a specially prepared magazine chain */ -#define magazine_chain_prev(mc) ((mc)->data) -#define magazine_chain_stamp(mc) ((mc)->next->data) -#define magazine_chain_uint_stamp(mc) GPOINTER_TO_UINT ((mc)->next->data) -#define magazine_chain_next(mc) ((mc)->next->next->data) -#define magazine_chain_count(mc) ((mc)->next->next->next->data) - -static void -magazine_cache_trim (Allocator *local_allocator, - guint ix, - guint stamp) -{ - /* g_mutex_lock (local_allocator->mutex); done by caller */ - /* trim magazine cache from tail */ - ChunkLink *current = magazine_chain_prev (local_allocator->magazines[ix]); - ChunkLink *trash = NULL; - while (!G_APPROX_VALUE (stamp, magazine_chain_uint_stamp (current), - local_allocator->config.working_set_msecs)) - { - /* unlink */ - ChunkLink *prev = magazine_chain_prev (current); - ChunkLink *next = magazine_chain_next (current); - magazine_chain_next (prev) = next; - magazine_chain_prev (next) = prev; - /* clear special fields, put on trash stack */ - magazine_chain_next (current) = NULL; - magazine_chain_count (current) = NULL; - magazine_chain_stamp (current) = NULL; - magazine_chain_prev (current) = trash; - trash = current; - /* fixup list head if required */ - if (current == local_allocator->magazines[ix]) - { - local_allocator->magazines[ix] = NULL; - break; - } - current = prev; - } - g_mutex_unlock (&local_allocator->magazine_mutex); - /* free trash */ - if (trash) - { - const gsize chunk_size = SLAB_CHUNK_SIZE (local_allocator, ix); - g_mutex_lock (&local_allocator->slab_mutex); - while (trash) - { - current = trash; - trash = magazine_chain_prev (current); - magazine_chain_prev (current) = NULL; /* clear special field */ - while (current) - { - ChunkLink *chunk = magazine_chain_pop_head (¤t); - slab_allocator_free_chunk (chunk_size, chunk); - } - } - g_mutex_unlock (&local_allocator->slab_mutex); - } -} - -static void -magazine_cache_push_magazine (guint ix, - ChunkLink *magazine_chunks, - gsize count) /* must be >= MIN_MAGAZINE_SIZE */ -{ - ChunkLink *current = magazine_chain_prepare_fields (magazine_chunks); - ChunkLink *next, *prev; - g_mutex_lock (&allocator->magazine_mutex); - /* add magazine at head */ - next = allocator->magazines[ix]; - if (next) - prev = magazine_chain_prev (next); - else - next = prev = current; - magazine_chain_next (prev) = current; - magazine_chain_prev (next) = current; - magazine_chain_prev (current) = prev; - magazine_chain_next (current) = next; - magazine_chain_count (current) = (gpointer) count; - /* stamp magazine */ - magazine_cache_update_stamp(); - magazine_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp); - allocator->magazines[ix] = current; - /* free old magazines beyond a certain threshold */ - magazine_cache_trim (allocator, ix, allocator->last_stamp); - /* g_mutex_unlock (allocator->mutex); was done by magazine_cache_trim() */ -} - -static ChunkLink* -magazine_cache_pop_magazine (guint ix, - gsize *countp) -{ - g_mutex_lock_a (&allocator->magazine_mutex, &allocator->contention_counters[ix]); - if (!allocator->magazines[ix]) - { - guint magazine_threshold = allocator_get_magazine_threshold (allocator, ix); - gsize i, chunk_size = SLAB_CHUNK_SIZE (allocator, ix); - ChunkLink *chunk, *head; - g_mutex_unlock (&allocator->magazine_mutex); - g_mutex_lock (&allocator->slab_mutex); - head = slab_allocator_alloc_chunk (chunk_size); - head->data = NULL; - chunk = head; - for (i = 1; i < magazine_threshold; i++) - { - chunk->next = slab_allocator_alloc_chunk (chunk_size); - chunk = chunk->next; - chunk->data = NULL; - } - chunk->next = NULL; - g_mutex_unlock (&allocator->slab_mutex); - *countp = i; - return head; - } - else - { - ChunkLink *current = allocator->magazines[ix]; - ChunkLink *prev = magazine_chain_prev (current); - ChunkLink *next = magazine_chain_next (current); - /* unlink */ - magazine_chain_next (prev) = next; - magazine_chain_prev (next) = prev; - allocator->magazines[ix] = next == current ? NULL : next; - g_mutex_unlock (&allocator->magazine_mutex); - /* clear special fields and hand out */ - *countp = (gsize) magazine_chain_count (current); - magazine_chain_prev (current) = NULL; - magazine_chain_next (current) = NULL; - magazine_chain_count (current) = NULL; - magazine_chain_stamp (current) = NULL; - return current; - } -} - -/* --- thread magazines --- */ -static void -private_thread_memory_cleanup (gpointer data) -{ - ThreadMemory *tmem = data; - const guint n_magazines = MAX_SLAB_INDEX (allocator); - guint ix; - for (ix = 0; ix < n_magazines; ix++) - { - Magazine *mags[2]; - guint j; - mags[0] = &tmem->magazine1[ix]; - mags[1] = &tmem->magazine2[ix]; - for (j = 0; j < 2; j++) - { - Magazine *mag = mags[j]; - if (mag->count >= MIN_MAGAZINE_SIZE) - magazine_cache_push_magazine (ix, mag->chunks, mag->count); - else - { - const gsize chunk_size = SLAB_CHUNK_SIZE (allocator, ix); - g_mutex_lock (&allocator->slab_mutex); - while (mag->chunks) - { - ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks); - slab_allocator_free_chunk (chunk_size, chunk); - } - g_mutex_unlock (&allocator->slab_mutex); - } - } - } - g_free (tmem); -} - -static void -thread_memory_magazine1_reload (ThreadMemory *tmem, - guint ix) -{ - Magazine *mag = &tmem->magazine1[ix]; - mem_assert (mag->chunks == NULL); /* ensure that we may reset mag->count */ - mag->count = 0; - mag->chunks = magazine_cache_pop_magazine (ix, &mag->count); -} - -static void -thread_memory_magazine2_unload (ThreadMemory *tmem, - guint ix) -{ - Magazine *mag = &tmem->magazine2[ix]; - magazine_cache_push_magazine (ix, mag->chunks, mag->count); - mag->chunks = NULL; - mag->count = 0; -} - -static inline void -thread_memory_swap_magazines (ThreadMemory *tmem, - guint ix) -{ - Magazine xmag = tmem->magazine1[ix]; - tmem->magazine1[ix] = tmem->magazine2[ix]; - tmem->magazine2[ix] = xmag; -} - -static inline gboolean -thread_memory_magazine1_is_empty (ThreadMemory *tmem, - guint ix) -{ - return tmem->magazine1[ix].chunks == NULL; -} - -static inline gboolean -thread_memory_magazine2_is_full (ThreadMemory *tmem, - guint ix) -{ - return tmem->magazine2[ix].count >= allocator_get_magazine_threshold (allocator, ix); -} - -static inline gpointer -thread_memory_magazine1_alloc (ThreadMemory *tmem, - guint ix) -{ - Magazine *mag = &tmem->magazine1[ix]; - ChunkLink *chunk = magazine_chain_pop_head (&mag->chunks); - if (G_LIKELY (mag->count > 0)) - mag->count--; - return chunk; -} - -static inline void -thread_memory_magazine2_free (ThreadMemory *tmem, - guint ix, - gpointer mem) -{ - Magazine *mag = &tmem->magazine2[ix]; - ChunkLink *chunk = mem; - chunk->data = NULL; - chunk->next = mag->chunks; - mag->chunks = chunk; - mag->count++; + /* deprecated, no implementation */ + return NULL; } /* --- API functions --- */ @@ -915,13 +125,14 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * * It calls g_slice_alloc() with `sizeof (@type)` and casts the * returned pointer to a pointer of the given type, avoiding a type - * cast in the source code. Note that the underlying slice allocation - * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE] - * environment variable. + * cast in the source code. * * This can never return %NULL as the minimum allocation size from * `sizeof (@type)` is 1 byte. * + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. + * * Returns: (not nullable): a pointer to the allocated block, cast to a pointer * to @type * @@ -938,13 +149,13 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * It calls g_slice_alloc0() with `sizeof (@type)` * and casts the returned pointer to a pointer of the given type, * avoiding a type cast in the source code. - * Note that the underlying slice allocation mechanism can - * be changed with the [`G_SLICE=always-malloc`][G_SLICE] - * environment variable. * * This can never return %NULL as the minimum allocation size from * `sizeof (@type)` is 1 byte. * + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. + * * Returns: (not nullable): a pointer to the allocated block, cast to a pointer * to @type * @@ -962,12 +173,12 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * It calls g_slice_copy() with `sizeof (@type)` * and casts the returned pointer to a pointer of the given type, * avoiding a type cast in the source code. - * Note that the underlying slice allocation mechanism can - * be changed with the [`G_SLICE=always-malloc`][G_SLICE] - * environment variable. * * This can never return %NULL. * + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. + * * Returns: (not nullable): a pointer to the allocated block, cast to a pointer * to @type * @@ -985,11 +196,12 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * It calls g_slice_free1() using `sizeof (type)` * as the block size. * Note that the exact release behaviour can be changed with the - * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see - * [`G_SLICE`][G_SLICE] for related debugging options. + * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable. * * If @mem is %NULL, this macro does nothing. * + * Since GLib 2.76 this always uses the system free() implementation internally. + * * Since: 2.10 */ @@ -1006,11 +218,12 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * a @next pointer (similar to #GSList). The name of the * @next field in @type is passed as third argument. * Note that the exact release behaviour can be changed with the - * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see - * [`G_SLICE`][G_SLICE] for related debugging options. + * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable. * * If @mem_chain is %NULL, this function does nothing. * + * Since GLib 2.76 this always uses the system free() implementation internally. + * * Since: 2.10 */ @@ -1018,17 +231,13 @@ thread_memory_magazine2_free (ThreadMemory *tmem, * g_slice_alloc: * @block_size: the number of bytes to allocate * - * Allocates a block of memory from the slice allocator. + * Allocates a block of memory from the libc allocator. * * The block address handed out can be expected to be aligned - * to at least `1 * sizeof (void*)`, though in general slices - * are `2 * sizeof (void*)` bytes aligned; if a `malloc()` - * fallback implementation is used instead, the alignment may - * be reduced in a libc dependent fashion. + * to at least `1 * sizeof (void*)`. * - * Note that the underlying slice allocation mechanism can - * be changed with the [`G_SLICE=always-malloc`][G_SLICE] - * environment variable. + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. * * Returns: a pointer to the allocated memory block, which will * be %NULL if and only if @mem_size is 0 @@ -1038,43 +247,9 @@ thread_memory_magazine2_free (ThreadMemory *tmem, gpointer g_slice_alloc (gsize mem_size) { - ThreadMemory *tmem; - gsize chunk_size; gpointer mem; - guint acat; - - /* This gets the private structure for this thread. If the private - * structure does not yet exist, it is created. - * - * This has a side effect of causing GSlice to be initialised, so it - * must come first. - */ - tmem = thread_memory_from_self (); - - chunk_size = P2ALIGN (mem_size); - acat = allocator_categorize (chunk_size); - if (G_LIKELY (acat == 1)) /* allocate through magazine layer */ - { - guint ix = SLAB_INDEX (allocator, chunk_size); - if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix))) - { - thread_memory_swap_magazines (tmem, ix); - if (G_UNLIKELY (thread_memory_magazine1_is_empty (tmem, ix))) - thread_memory_magazine1_reload (tmem, ix); - } - mem = thread_memory_magazine1_alloc (tmem, ix); - } - else if (acat == 2) /* allocate through slab allocator */ - { - g_mutex_lock (&allocator->slab_mutex); - mem = slab_allocator_alloc_chunk (chunk_size); - g_mutex_unlock (&allocator->slab_mutex); - } - else /* delegate to system malloc */ - mem = g_malloc (mem_size); - if (G_UNLIKELY (allocator->config.debug_blocks)) - smc_notify_alloc (mem, mem_size); + mem = g_malloc (mem_size); TRACE (GLIB_SLICE_ALLOC((void*)mem, mem_size)); return mem; @@ -1085,9 +260,10 @@ g_slice_alloc (gsize mem_size) * @block_size: the number of bytes to allocate * * Allocates a block of memory via g_slice_alloc() and initializes - * the returned memory to 0. Note that the underlying slice allocation - * mechanism can be changed with the [`G_SLICE=always-malloc`][G_SLICE] - * environment variable. + * the returned memory to 0. + * + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. * * Returns: a pointer to the allocated block, which will be %NULL if and only * if @mem_size is 0 @@ -1113,6 +289,9 @@ g_slice_alloc0 (gsize mem_size) * * @mem_block must be non-%NULL if @block_size is non-zero. * + * Since GLib 2.76 this always uses the system malloc() implementation + * internally. + * * Returns: a pointer to the allocated memory block, which will be %NULL if and * only if @mem_size is 0 * @@ -1139,51 +318,21 @@ g_slice_copy (gsize mem_size, * g_slice_alloc0() and the @block_size has to match the size * specified upon allocation. Note that the exact release behaviour * can be changed with the [`G_DEBUG=gc-friendly`][G_DEBUG] environment - * variable, also see [`G_SLICE`][G_SLICE] for related debugging options. + * variable. * * If @mem_block is %NULL, this function does nothing. * + * Since GLib 2.76 this always uses the system free() implementation internally. + * * Since: 2.10 */ void g_slice_free1 (gsize mem_size, gpointer mem_block) { - gsize chunk_size = P2ALIGN (mem_size); - guint acat = allocator_categorize (chunk_size); - if (G_UNLIKELY (!mem_block)) - return; - if (G_UNLIKELY (allocator->config.debug_blocks) && - !smc_notify_free (mem_block, mem_size)) - abort(); - if (G_LIKELY (acat == 1)) /* allocate through magazine layer */ - { - ThreadMemory *tmem = thread_memory_from_self(); - guint ix = SLAB_INDEX (allocator, chunk_size); - if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix))) - { - thread_memory_swap_magazines (tmem, ix); - if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix))) - thread_memory_magazine2_unload (tmem, ix); - } - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (mem_block, 0, chunk_size); - thread_memory_magazine2_free (tmem, ix, mem_block); - } - else if (acat == 2) /* allocate through slab allocator */ - { - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (mem_block, 0, chunk_size); - g_mutex_lock (&allocator->slab_mutex); - slab_allocator_free_chunk (chunk_size, mem_block); - g_mutex_unlock (&allocator->slab_mutex); - } - else /* delegate to system malloc */ - { - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (mem_block, 0, mem_size); - g_free (mem_block); - } + if (G_UNLIKELY (g_mem_gc_friendly)) + memset (mem_block, 0, mem_size); + g_free (mem_block); TRACE (GLIB_SLICE_FREE((void*)mem_block, mem_size)); } @@ -1200,11 +349,12 @@ g_slice_free1 (gsize mem_size, * @next pointer (similar to #GSList). The offset of the @next * field in each block is passed as third argument. * Note that the exact release behaviour can be changed with the - * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable, also see - * [`G_SLICE`][G_SLICE] for related debugging options. + * [`G_DEBUG=gc-friendly`][G_DEBUG] environment variable. * * If @mem_chain is %NULL, this function does nothing. * + * Since GLib 2.76 this always uses the system free() implementation internally. + * * Since: 2.10 */ void @@ -1213,589 +363,20 @@ g_slice_free_chain_with_offset (gsize mem_size, gsize next_offset) { gpointer slice = mem_chain; - /* while the thread magazines and the magazine cache are implemented so that - * they can easily be extended to allow for free lists containing more free - * lists for the first level nodes, which would allow O(1) freeing in this - * function, the benefit of such an extension is questionable, because: - * - the magazine size counts will become mere lower bounds which confuses - * the code adapting to lock contention; - * - freeing a single node to the thread magazines is very fast, so this - * O(list_length) operation is multiplied by a fairly small factor; - * - memory usage histograms on larger applications seem to indicate that - * the amount of released multi node lists is negligible in comparison - * to single node releases. - * - the major performance bottle neck, namely g_private_get() or - * g_mutex_lock()/g_mutex_unlock() has already been moved out of the - * inner loop for freeing chained slices. - */ - gsize chunk_size = P2ALIGN (mem_size); - guint acat = allocator_categorize (chunk_size); - if (G_LIKELY (acat == 1)) /* allocate through magazine layer */ + while (slice) { - ThreadMemory *tmem = thread_memory_from_self(); - guint ix = SLAB_INDEX (allocator, chunk_size); - while (slice) - { - guint8 *current = slice; - slice = *(gpointer*) (current + next_offset); - if (G_UNLIKELY (allocator->config.debug_blocks) && - !smc_notify_free (current, mem_size)) - abort(); - if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix))) - { - thread_memory_swap_magazines (tmem, ix); - if (G_UNLIKELY (thread_memory_magazine2_is_full (tmem, ix))) - thread_memory_magazine2_unload (tmem, ix); - } - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (current, 0, chunk_size); - thread_memory_magazine2_free (tmem, ix, current); - } + guint8 *current = slice; + slice = *(gpointer *) (current + next_offset); + if (G_UNLIKELY (g_mem_gc_friendly)) + memset (current, 0, mem_size); + g_free (current); } - else if (acat == 2) /* allocate through slab allocator */ - { - g_mutex_lock (&allocator->slab_mutex); - while (slice) - { - guint8 *current = slice; - slice = *(gpointer*) (current + next_offset); - if (G_UNLIKELY (allocator->config.debug_blocks) && - !smc_notify_free (current, mem_size)) - abort(); - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (current, 0, chunk_size); - slab_allocator_free_chunk (chunk_size, current); - } - g_mutex_unlock (&allocator->slab_mutex); - } - else /* delegate to system malloc */ - while (slice) - { - guint8 *current = slice; - slice = *(gpointer*) (current + next_offset); - if (G_UNLIKELY (allocator->config.debug_blocks) && - !smc_notify_free (current, mem_size)) - abort(); - if (G_UNLIKELY (g_mem_gc_friendly)) - memset (current, 0, mem_size); - g_free (current); - } -} - -/* --- single page allocator --- */ -static void -allocator_slab_stack_push (Allocator *local_allocator, - guint ix, - SlabInfo *sinfo) -{ - /* insert slab at slab ring head */ - if (!local_allocator->slab_stack[ix]) - { - sinfo->next = sinfo; - sinfo->prev = sinfo; - } - else - { - SlabInfo *next = local_allocator->slab_stack[ix], *prev = next->prev; - next->prev = sinfo; - prev->next = sinfo; - sinfo->next = next; - sinfo->prev = prev; - } - local_allocator->slab_stack[ix] = sinfo; -} - -static gsize -allocator_aligned_page_size (Allocator *local_allocator, - gsize n_bytes) -{ - gsize val = (gsize) 1 << g_bit_storage (n_bytes - 1); - val = MAX (val, local_allocator->min_page_size); - return val; -} - -static void -allocator_add_slab (Allocator *local_allocator, - guint ix, - gsize chunk_size) -{ - ChunkLink *chunk; - SlabInfo *sinfo; - gsize addr, padding, n_chunks, color = 0; - gsize page_size; - int errsv; - gpointer aligned_memory; - guint8 *mem; - guint i; - - page_size = allocator_aligned_page_size (local_allocator, SLAB_BPAGE_SIZE (local_allocator, chunk_size)); - /* allocate 1 page for the chunks and the slab */ - aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING); - errsv = errno; - mem = aligned_memory; - - if (!mem) - { - const gchar *syserr = strerror (errsv); - mem_error ("failed to allocate %u bytes (alignment: %u): %s\n", - (guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr); - } - /* mask page address */ - addr = ((gsize) mem / page_size) * page_size; - /* assert alignment */ - mem_assert (aligned_memory == (gpointer) addr); - /* basic slab info setup */ - sinfo = (SlabInfo*) (mem + page_size - SLAB_INFO_SIZE); - sinfo->n_allocated = 0; - sinfo->chunks = NULL; - /* figure cache colorization */ - n_chunks = ((guint8*) sinfo - mem) / chunk_size; - padding = ((guint8*) sinfo - mem) - n_chunks * chunk_size; - if (padding) - { - color = (local_allocator->color_accu * P2ALIGNMENT) % padding; - local_allocator->color_accu += local_allocator->config.color_increment; - } - /* add chunks to free list */ - chunk = (ChunkLink*) (mem + color); - sinfo->chunks = chunk; - for (i = 0; i < n_chunks - 1; i++) - { - chunk->next = (ChunkLink*) ((guint8*) chunk + chunk_size); - chunk = chunk->next; - } - chunk->next = NULL; /* last chunk */ - /* add slab to slab ring */ - allocator_slab_stack_push (local_allocator, ix, sinfo); -} - -static gpointer -slab_allocator_alloc_chunk (gsize chunk_size) -{ - ChunkLink *chunk; - guint ix = SLAB_INDEX (allocator, chunk_size); - /* ensure non-empty slab */ - if (!allocator->slab_stack[ix] || !allocator->slab_stack[ix]->chunks) - allocator_add_slab (allocator, ix, chunk_size); - /* allocate chunk */ - chunk = allocator->slab_stack[ix]->chunks; - allocator->slab_stack[ix]->chunks = chunk->next; - allocator->slab_stack[ix]->n_allocated++; - /* rotate empty slabs */ - if (!allocator->slab_stack[ix]->chunks) - allocator->slab_stack[ix] = allocator->slab_stack[ix]->next; - return chunk; -} - -static void -slab_allocator_free_chunk (gsize chunk_size, - gpointer mem) -{ - ChunkLink *chunk; - gboolean was_empty; - guint ix = SLAB_INDEX (allocator, chunk_size); - gsize page_size = allocator_aligned_page_size (allocator, SLAB_BPAGE_SIZE (allocator, chunk_size)); - gsize addr = ((gsize) mem / page_size) * page_size; - /* mask page address */ - guint8 *page = (guint8*) addr; - SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE); - /* assert valid chunk count */ - mem_assert (sinfo->n_allocated > 0); - /* add chunk to free list */ - was_empty = sinfo->chunks == NULL; - chunk = (ChunkLink*) mem; - chunk->next = sinfo->chunks; - sinfo->chunks = chunk; - sinfo->n_allocated--; - /* keep slab ring partially sorted, empty slabs at end */ - if (was_empty) - { - /* unlink slab */ - SlabInfo *next = sinfo->next, *prev = sinfo->prev; - next->prev = prev; - prev->next = next; - if (allocator->slab_stack[ix] == sinfo) - allocator->slab_stack[ix] = next == sinfo ? NULL : next; - /* insert slab at head */ - allocator_slab_stack_push (allocator, ix, sinfo); - } - /* eagerly free complete unused slabs */ - if (!sinfo->n_allocated) - { - /* unlink slab */ - SlabInfo *next = sinfo->next, *prev = sinfo->prev; - next->prev = prev; - prev->next = next; - if (allocator->slab_stack[ix] == sinfo) - allocator->slab_stack[ix] = next == sinfo ? NULL : next; - /* free slab */ - allocator_memfree (page_size, page); - } -} - -/* --- memalign implementation --- */ -#ifdef HAVE_MALLOC_H -#include /* memalign() */ -#endif - -/* from config.h: - * define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, - * define HAVE_MEMALIGN 1 // if free(memalign(3)) works, - * define HAVE_VALLOC 1 // if free(valloc(3)) works, or - * if none is provided, we implement malloc(3)-based alloc-only page alignment - */ - -#if !(HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC) -G_GNUC_BEGIN_IGNORE_DEPRECATIONS -static GTrashStack *compat_valloc_trash = NULL; -G_GNUC_END_IGNORE_DEPRECATIONS -#endif - -static gpointer -allocator_memalign (gsize alignment, - gsize memsize) -{ - gpointer aligned_memory = NULL; - gint err = ENOMEM; -#if HAVE_POSIX_MEMALIGN - err = posix_memalign (&aligned_memory, alignment, memsize); -#elif HAVE_MEMALIGN - errno = 0; - aligned_memory = memalign (alignment, memsize); - err = errno; -#elif HAVE_VALLOC - errno = 0; - aligned_memory = valloc (memsize); - err = errno; -#else - /* simplistic non-freeing page allocator */ - mem_assert (alignment == sys_page_size); - mem_assert (memsize <= sys_page_size); - if (!compat_valloc_trash) - { - const guint n_pages = 16; - guint8 *mem = malloc (n_pages * sys_page_size); - err = errno; - if (mem) - { - gint i = n_pages; - guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size); - if (amem != mem) - i--; /* mem wasn't page aligned */ - G_GNUC_BEGIN_IGNORE_DEPRECATIONS - while (--i >= 0) - g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size); - G_GNUC_END_IGNORE_DEPRECATIONS - } - } - G_GNUC_BEGIN_IGNORE_DEPRECATIONS - aligned_memory = g_trash_stack_pop (&compat_valloc_trash); - G_GNUC_END_IGNORE_DEPRECATIONS -#endif - if (!aligned_memory) - errno = err; - return aligned_memory; -} - -static void -allocator_memfree (gsize memsize, - gpointer mem) -{ -#if HAVE_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC - free (mem); -#else - mem_assert (memsize <= sys_page_size); - G_GNUC_BEGIN_IGNORE_DEPRECATIONS - g_trash_stack_push (&compat_valloc_trash, mem); - G_GNUC_END_IGNORE_DEPRECATIONS -#endif -} - -static void -mem_error (const char *format, - ...) -{ - const char *pname; - va_list args; - /* at least, put out "MEMORY-ERROR", in case we segfault during the rest of the function */ - fputs ("\n***MEMORY-ERROR***: ", stderr); - pname = g_get_prgname(); - g_fprintf (stderr, "%s[%ld]: GSlice: ", pname ? pname : "", (long)getpid()); - va_start (args, format); - g_vfprintf (stderr, format, args); - va_end (args); - fputs ("\n", stderr); - abort(); - _exit (1); -} - -/* --- g-slice memory checker tree --- */ -typedef size_t SmcKType; /* key type */ -typedef size_t SmcVType; /* value type */ -typedef struct { - SmcKType key; - SmcVType value; -} SmcEntry; -static void smc_tree_insert (SmcKType key, - SmcVType value); -static gboolean smc_tree_lookup (SmcKType key, - SmcVType *value_p); -static gboolean smc_tree_remove (SmcKType key); - - -/* --- g-slice memory checker implementation --- */ -static void -smc_notify_alloc (void *pointer, - size_t size) -{ - size_t address = (size_t) pointer; - if (pointer) - smc_tree_insert (address, size); -} - -#if 0 -static void -smc_notify_ignore (void *pointer) -{ - size_t address = (size_t) pointer; - if (pointer) - smc_tree_remove (address); -} -#endif - -static int -smc_notify_free (void *pointer, - size_t size) -{ - size_t address = (size_t) pointer; - SmcVType real_size; - gboolean found_one; - - if (!pointer) - return 1; /* ignore */ - found_one = smc_tree_lookup (address, &real_size); - if (!found_one) - { - g_fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size); - return 0; - } - if (real_size != size && (real_size || size)) - { - 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); - return 0; - } - if (!smc_tree_remove (address)) - { - g_fprintf (stderr, "GSlice: MemChecker: attempt to release non-allocated block: %p size=%" G_GSIZE_FORMAT "\n", pointer, size); - return 0; - } - return 1; /* all fine */ -} - -/* --- g-slice memory checker tree implementation --- */ -#define SMC_TRUNK_COUNT (4093 /* 16381 */) /* prime, to distribute trunk collisions (big, allocated just once) */ -#define SMC_BRANCH_COUNT (511) /* prime, to distribute branch collisions */ -#define SMC_TRUNK_EXTENT (SMC_BRANCH_COUNT * 2039) /* key address space per trunk, should distribute uniformly across BRANCH_COUNT */ -#define SMC_TRUNK_HASH(k) ((k / SMC_TRUNK_EXTENT) % SMC_TRUNK_COUNT) /* generate new trunk hash per megabyte (roughly) */ -#define SMC_BRANCH_HASH(k) (k % SMC_BRANCH_COUNT) - -typedef struct { - SmcEntry *entries; - unsigned int n_entries; -} SmcBranch; - -static SmcBranch **smc_tree_root = NULL; - -static void -smc_tree_abort (int errval) -{ - const char *syserr = strerror (errval); - mem_error ("MemChecker: failure in debugging tree: %s", syserr); -} - -static inline SmcEntry* -smc_tree_branch_grow_L (SmcBranch *branch, - unsigned int index) -{ - unsigned int old_size = branch->n_entries * sizeof (branch->entries[0]); - unsigned int new_size = old_size + sizeof (branch->entries[0]); - SmcEntry *entry; - mem_assert (index <= branch->n_entries); - branch->entries = (SmcEntry*) realloc (branch->entries, new_size); - if (!branch->entries) - smc_tree_abort (errno); - entry = branch->entries + index; - memmove (entry + 1, entry, (branch->n_entries - index) * sizeof (entry[0])); - branch->n_entries += 1; - return entry; -} - -static inline SmcEntry* -smc_tree_branch_lookup_nearest_L (SmcBranch *branch, - SmcKType key) -{ - unsigned int n_nodes = branch->n_entries, offs = 0; - SmcEntry *check = branch->entries; - int cmp = 0; - while (offs < n_nodes) - { - unsigned int i = (offs + n_nodes) >> 1; - check = branch->entries + i; - cmp = key < check->key ? -1 : key != check->key; - if (cmp == 0) - return check; /* return exact match */ - else if (cmp < 0) - n_nodes = i; - else /* (cmp > 0) */ - offs = i + 1; - } - /* check points at last mismatch, cmp > 0 indicates greater key */ - return cmp > 0 ? check + 1 : check; /* return insertion position for inexact match */ -} - -static void -smc_tree_insert (SmcKType key, - SmcVType value) -{ - unsigned int ix0, ix1; - SmcEntry *entry; - - g_mutex_lock (&smc_tree_mutex); - ix0 = SMC_TRUNK_HASH (key); - ix1 = SMC_BRANCH_HASH (key); - if (!smc_tree_root) - { - smc_tree_root = calloc (SMC_TRUNK_COUNT, sizeof (smc_tree_root[0])); - if (!smc_tree_root) - smc_tree_abort (errno); - } - if (!smc_tree_root[ix0]) - { - smc_tree_root[ix0] = calloc (SMC_BRANCH_COUNT, sizeof (smc_tree_root[0][0])); - if (!smc_tree_root[ix0]) - smc_tree_abort (errno); - } - entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key); - if (!entry || /* need create */ - entry >= smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries || /* need append */ - entry->key != key) /* need insert */ - entry = smc_tree_branch_grow_L (&smc_tree_root[ix0][ix1], entry - smc_tree_root[ix0][ix1].entries); - entry->key = key; - entry->value = value; - g_mutex_unlock (&smc_tree_mutex); -} - -static gboolean -smc_tree_lookup (SmcKType key, - SmcVType *value_p) -{ - SmcEntry *entry = NULL; - unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key); - gboolean found_one = FALSE; - *value_p = 0; - g_mutex_lock (&smc_tree_mutex); - if (smc_tree_root && smc_tree_root[ix0]) - { - entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key); - if (entry && - entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries && - entry->key == key) - { - found_one = TRUE; - *value_p = entry->value; - } - } - g_mutex_unlock (&smc_tree_mutex); - return found_one; -} - -static gboolean -smc_tree_remove (SmcKType key) -{ - unsigned int ix0 = SMC_TRUNK_HASH (key), ix1 = SMC_BRANCH_HASH (key); - gboolean found_one = FALSE; - g_mutex_lock (&smc_tree_mutex); - if (smc_tree_root && smc_tree_root[ix0]) - { - SmcEntry *entry = smc_tree_branch_lookup_nearest_L (&smc_tree_root[ix0][ix1], key); - if (entry && - entry < smc_tree_root[ix0][ix1].entries + smc_tree_root[ix0][ix1].n_entries && - entry->key == key) - { - unsigned int i = entry - smc_tree_root[ix0][ix1].entries; - smc_tree_root[ix0][ix1].n_entries -= 1; - memmove (entry, entry + 1, (smc_tree_root[ix0][ix1].n_entries - i) * sizeof (entry[0])); - if (!smc_tree_root[ix0][ix1].n_entries) - { - /* avoid useless pressure on the memory system */ - free (smc_tree_root[ix0][ix1].entries); - smc_tree_root[ix0][ix1].entries = NULL; - } - found_one = TRUE; - } - } - g_mutex_unlock (&smc_tree_mutex); - return found_one; } #ifdef G_ENABLE_DEBUG void g_slice_debug_tree_statistics (void) { - g_mutex_lock (&smc_tree_mutex); - if (smc_tree_root) - { - unsigned int i, j, t = 0, o = 0, b = 0, su = 0, ex = 0, en = 4294967295u; - double tf, bf; - for (i = 0; i < SMC_TRUNK_COUNT; i++) - if (smc_tree_root[i]) - { - t++; - for (j = 0; j < SMC_BRANCH_COUNT; j++) - if (smc_tree_root[i][j].n_entries) - { - b++; - su += smc_tree_root[i][j].n_entries; - en = MIN (en, smc_tree_root[i][j].n_entries); - ex = MAX (ex, smc_tree_root[i][j].n_entries); - } - else if (smc_tree_root[i][j].entries) - o++; /* formerly used, now empty */ - } - en = b ? en : 0; - tf = MAX (t, 1.0); /* max(1) to be a valid divisor */ - bf = MAX (b, 1.0); /* max(1) to be a valid divisor */ - g_fprintf (stderr, "GSlice: MemChecker: %u trunks, %u branches, %u old branches\n", t, b, o); - g_fprintf (stderr, "GSlice: MemChecker: %f branches per trunk, %.2f%% utilization\n", - b / tf, - 100.0 - (SMC_BRANCH_COUNT - b / tf) / (0.01 * SMC_BRANCH_COUNT)); - g_fprintf (stderr, "GSlice: MemChecker: %f entries per branch, %u minimum, %u maximum\n", - su / bf, en, ex); - } - else - g_fprintf (stderr, "GSlice: MemChecker: root=NULL\n"); - g_mutex_unlock (&smc_tree_mutex); - - /* sample statistics (beast + GSLice + 24h scripted core & GUI activity): - * PID %CPU %MEM VSZ RSS COMMAND - * 8887 30.3 45.8 456068 414856 beast-0.7.1 empty.bse - * $ cat /proc/8887/statm # total-program-size resident-set-size shared-pages text/code data/stack library dirty-pages - * 114017 103714 2354 344 0 108676 0 - * $ cat /proc/8887/status - * Name: beast-0.7.1 - * VmSize: 456068 kB - * VmLck: 0 kB - * VmRSS: 414856 kB - * VmData: 434620 kB - * VmStk: 84 kB - * VmExe: 1376 kB - * VmLib: 13036 kB - * VmPTE: 456 kB - * Threads: 3 - * (gdb) print g_slice_debug_tree_statistics () - * GSlice: MemChecker: 422 trunks, 213068 branches, 0 old branches - * GSlice: MemChecker: 504.900474 branches per trunk, 98.81% utilization - * GSlice: MemChecker: 4.965039 entries per branch, 1 minimum, 37 maximum - */ + g_fprintf (stderr, "GSlice: Implementation dropped in GLib 2.76\n"); } #endif /* G_ENABLE_DEBUG */