/* GLIB sliced memory - fast concurrent memory chunk allocator
* Copyright (C) 2005 Tim Janik
* Portions copyright (c) 2006 Nokia Corporation. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
/* MT safe */
#include "config.h"
#if defined HAVE_POSIX_MEMALIGN && defined POSIX_MEMALIGN_WITH_COMPLIANT_ALLOCS
# define HAVE_COMPLIANT_POSIX_MEMALIGN 1
#endif
#ifdef HAVE_COMPLIANT_POSIX_MEMALIGN
#define _XOPEN_SOURCE 600 /* posix_memalign() */
#endif
#include <stdlib.h> /* posix_memalign() */
#include <string.h>
#include <errno.h>
#include "gmem.h" /* gslice.h */
#include "gthreadinit.h"
#include "galias.h"
#include "glib.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h> /* sysconf() */
#endif
#ifdef G_OS_WIN32
#include <windows.h>
#include <process.h>
#endif
#ifdef __SYMBIAN32__
#include <glib_wsd.h>
#endif /* __SYMBIAN32__ */
#if EMULATOR
#define g_thread_functions_for_glib_use (*_g_thread_functions_for_glib_use())
#define g_thread_use_default_impl (*_g_thread_use_default_impl())
#define g_mem_gc_friendly (*_g_mem_gc_friendly())
#endif /* EMULATOR */
/* 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 retrive the
* thread handle.
* - the magazine cache. allocating and freeing chunks to/from threads only
* occours 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 */
static void mem_error (const char *format, ...) G_GNUC_PRINTF (1,2);
#define mem_assert(cond) do { if (G_LIKELY (cond)) ; else mem_error ("assertion failed: %s", #cond); } while (0)
/* --- structures --- */
#if !(EMULATOR)
typedef struct _ChunkLink ChunkLink;
typedef struct _SlabInfo SlabInfo;
#endif /* !(EMULATOR) */
typedef struct _CachedMagazine CachedMagazine;
#if !(EMULATOR)
struct _ChunkLink {
ChunkLink *next;
ChunkLink *data;
};
struct _SlabInfo {
ChunkLink *chunks;
guint n_allocated;
SlabInfo *next, *prev;
};
#endif /* !(EMULATOR) */
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;
#if !(EMULATOR)
typedef struct {
gboolean always_malloc;
gboolean bypass_magazines;
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;
#endif /* !(EMULATOR)
/* --- 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);
#if EMULATOR
static inline gsize allocator_get_magazine_threshold (Allocator *allocator1,
guint ix);
#else
static inline gsize allocator_get_magazine_threshold (Allocator *allocator,
guint ix);
#endif /* EMULATOR */
/* --- variables --- */
#if EMULATOR
PLS(private_thread_memory,gslice,GPrivate *)
PLS(sys_page_size,gslice,gsize)
PLS_ARRAY(allocator,gslice,Allocator)
PLS(slice_config,gslice,SliceConfig)
#define private_thread_memory (*FUNCTION_NAME(private_thread_memory ,gslice)())
#define sys_page_size (*FUNCTION_NAME(sys_page_size ,gslice)())
#define allocator (FUNCTION_NAME(allocator ,gslice)())
#define slice_config (*FUNCTION_NAME(slice_config ,gslice)())
#else
static GPrivate *private_thread_memory = NULL;
static gsize sys_page_size = 0;
static Allocator allocator[1] = { { 0, }, };
static SliceConfig slice_config = {
FALSE, /* always_malloc */
FALSE, /* bypass_magazines */
15 * 1000, /* working_set_msecs */
1, /* color increment, alt: 0x7fffffff */
};
#endif /* EMULATOR */
/* --- auxillary funcitons --- */
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;
default: ;
}
}
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;
}
}
gint64*
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_memdup (array, sizeof (array[0]) * *n_values);
default:
return NULL;
}
}
static void
slice_config_init (SliceConfig *config)
{
/* don't use g_malloc/g_message here */
gchar buffer[1024];
const gchar *val = _g_getenv_nomalloc ("G_SLICE", buffer);
static const GDebugKey keys[] = {
{ "always-malloc", 1 << 0 },
};
gint flags = !val ? 0 : g_parse_debug_string (val, keys, G_N_ELEMENTS (keys));
*config = slice_config;
if (flags & (1 << 0)) /* always-malloc */
{
config->always_malloc = TRUE;
}
}
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);
// If the allocator is configured in such a way that the glib always uses
// system malloc, then we dont need to allocate the book keeping array.
// Thats why we return after that check and when it is successful.
#ifdef __SYMBIAN32__
if(allocator->config.always_malloc)
return;
#endif /* __SYMBIAN32__ */
allocator->min_page_size = sys_page_size;
#if HAVE_COMPLIANT_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 incresing 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
allocator->magazine_mutex = NULL; /* _g_slice_thread_init_nomessage() */
allocator->magazines = g_new0 (ChunkLink*, MAX_SLAB_INDEX (allocator));
allocator->contention_counters = g_new0 (guint, MAX_SLAB_INDEX (allocator));
allocator->mutex_counter = 0;
allocator->stamp_counter = MAX_STAMP_COUNTER; /* force initial update */
allocator->last_stamp = 0;
allocator->slab_mutex = NULL; /* _g_slice_thread_init_nomessage() */
allocator->slab_stack = g_new0 (SlabInfo*, MAX_SLAB_INDEX (allocator));
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 */
/* at this point, g_mem_gc_friendly() should be initialized, this
* should have been accomplished by the above g_malloc/g_new calls
*/
}
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 */
/* the above will fail (max_slab_chunk_size_for_magazine_cache == 0) if the
* allocator is still uninitialized, or if we are not configured to use the
* magazine cache.
*/
if (!sys_page_size)
g_slice_init_nomessage ();
// If the allocator is configured in such a way that the glib always uses
// system malloc, then we dont need to allocate the book keeping array.
// Thats why we return 0 after that check and when it is successful.
#ifdef __SYMBIAN32__
if(allocator->config.always_malloc)
return 0;
#endif /* __SYMBIAN32__*/
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() */
}
void
_g_slice_thread_init_nomessage (void)
{
/* we may not use g_error() or friends here */
if (!sys_page_size)
g_slice_init_nomessage();
private_thread_memory = g_private_new (private_thread_memory_cleanup);
allocator->magazine_mutex = g_mutex_new();
allocator->slab_mutex = g_mutex_new();
}
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))
{
const guint n_magazines = MAX_SLAB_INDEX (allocator);
tmem = g_malloc0 (sizeof (ThreadMemory) + sizeof (Magazine) * 2 * n_magazines);
tmem->magazine1 = (Magazine*) (tmem + 1);
tmem->magazine2 = &tmem->magazine1[n_magazines];
g_private_set (private_thread_memory, tmem);
}
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 *allocator1,
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 (allocator1, ix);
guint threshold = MAX (MIN_MAGAZINE_SIZE, allocator1->max_page_size / MAX (5 * chunk_size, 5 * 32));
guint contention_counter = allocator1->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)
{
GTimeVal tv;
g_get_current_time (&tv);
allocator->last_stamp = tv.tv_sec * 1000 + tv.tv_usec / 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)
#ifdef __SYMBIAN32__
static void
magazine_cache_trim (Allocator *allocator1,
guint ix,
guint stamp)
#else
static void
magazine_cache_trim (Allocator *allocator,
guint ix,
guint stamp)
#endif /* __SYMBIAN32__ */
{
/* g_mutex_lock (allocator->mutex); done by caller */
/* trim magazine cache from tail */
ChunkLink *current = magazine_chain_prev (allocator1->magazines[ix]);
ChunkLink *trash = NULL;
while (ABS (stamp - magazine_chain_uint_stamp (current)) >= allocator1->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 == allocator1->magazines[ix])
{
allocator1->magazines[ix] = NULL;
break;
}
current = prev;
}
g_mutex_unlock (allocator1->magazine_mutex);
/* free trash */
if (trash)
{
const gsize chunk_size = SLAB_CHUNK_SIZE (allocator1, ix);
g_mutex_lock (allocator1->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 (allocator1->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_chain_stamp (current) = GUINT_TO_POINTER (allocator->last_stamp);
magazine_cache_update_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++;
}
/* --- API functions --- */
EXPORT_C gpointer
g_slice_alloc (gsize mem_size)
{
gsize chunk_size;
gpointer mem;
guint acat;
chunk_size = P2ALIGN (mem_size);
acat = allocator_categorize (chunk_size);
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_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);
return mem;
}
EXPORT_C gpointer
g_slice_alloc0 (gsize mem_size)
{
gpointer mem = g_slice_alloc (mem_size);
if (mem)
memset (mem, 0, mem_size);
return mem;
}
EXPORT_C 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_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);
}
}
EXPORT_C void
g_slice_free_chain_with_offset (gsize mem_size,
gpointer mem_chain,
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 */
{
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 (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);
}
}
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 (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 (g_mem_gc_friendly))
memset (current, 0, mem_size);
g_free (current);
}
}
/* --- single page allocator --- */
#ifdef __SYMBIAN32__
static void
allocator_slab_stack_push (Allocator *allocator1,
guint ix,
SlabInfo *sinfo)
#else
static void
allocator_slab_stack_push (Allocator *allocator,
guint ix,
SlabInfo *sinfo)
#endif /* __SYMBIAN32__ */
{
/* insert slab at slab ring head */
if (!allocator1->slab_stack[ix])
{
sinfo->next = sinfo;
sinfo->prev = sinfo;
}
else
{
SlabInfo *next = allocator1->slab_stack[ix], *prev = next->prev;
next->prev = sinfo;
prev->next = sinfo;
sinfo->next = next;
sinfo->prev = prev;
}
allocator1->slab_stack[ix] = sinfo;
}
#ifdef __SYMBIAN32__
static gsize
allocator_aligned_page_size (Allocator *allocator1,
gsize n_bytes)
#else
static gsize
allocator_aligned_page_size (Allocator *allocator,
gsize n_bytes)
#endif /* __SYMBIAN32__ */
{
gsize val = 1 << g_bit_storage (n_bytes - 1);
val = MAX (val, allocator1->min_page_size);
return val;
}
#ifdef __SYMBIAN32__
static void
allocator_add_slab (Allocator *allocator1,
guint ix,
gsize chunk_size)
#else
static void
allocator_add_slab (Allocator *allocator,
guint ix,
gsize chunk_size)
#endif /* __SYMBIAN32__ */
{
ChunkLink *chunk;
SlabInfo *sinfo;
gsize addr, padding, n_chunks, color = 0;
gsize page_size = allocator_aligned_page_size (allocator1, SLAB_BPAGE_SIZE (allocator1, chunk_size));
/* allocate 1 page for the chunks and the slab */
gpointer aligned_memory = allocator_memalign (page_size, page_size - NATIVE_MALLOC_PADDING);
guint8 *mem = aligned_memory;
guint i;
if (!mem)
{
const gchar *syserr = "unknown error";
#if HAVE_STRERROR
syserr = strerror (errno);
#endif
mem_error ("failed to allocate %u bytes (alignment: %u): %s\n",
(guint) (page_size - NATIVE_MALLOC_PADDING), (guint) page_size, syserr);
}
/* mask page adress */
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 = (allocator1->color_accu * P2ALIGNMENT) % padding;
allocator1->color_accu += allocator1->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 (allocator1, 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;
#ifdef MOBILE_PORT
guint16 offset;
#endif//MOBILE_PORT
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 adress */
guint8 *page = (guint8*) addr;
SlabInfo *sinfo = (SlabInfo*) (page + page_size - SLAB_INFO_SIZE);
/* assert valid chunk count */
mem_assert (sinfo->n_allocated > 0);
#ifdef MOBILE_PORT
offset = *((guint16*)(page + page_size - NATIVE_MALLOC_PADDING));
#endif//MOBILE_PORT
/* 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 */
#ifndef MOBILE_PORT
allocator_memfree (page_size, page);
#else//MOBILE_PORT
allocator_memfree (page_size, page - offset);
#endif//MOBILE_PORT
}
}
/* --- memalign implementation --- */
#ifdef HAVE_MALLOC_H
#include <malloc.h> /* memalign() *///puneet
#endif
/* from config.h:
* define HAVE_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works, <stdlib.h>
* define HAVE_COMPLIANT_POSIX_MEMALIGN 1 // if free(posix_memalign(3)) works for sizes != 2^n, <stdlib.h>
* define HAVE_MEMALIGN 1 // if free(memalign(3)) works, <malloc.h>
* define HAVE_VALLOC 1 // if free(valloc(3)) works, <stdlib.h> or <malloc.h>
* if none is provided, we implement malloc(3)-based alloc-only page alignment
*/
#if !(HAVE_COMPLIANT_POSIX_MEMALIGN || HAVE_MEMALIGN || HAVE_VALLOC)
#if EMULATOR
PLS(compat_valloc_trash,gslice,GTrashStack *)
#define compat_valloc_trash (*FUNCTION_NAME(compat_valloc_trash,gslice)())
#else
static GTrashStack *compat_valloc_trash = NULL;
#endif /* EMULATOR */
#endif
static gpointer
allocator_memalign (gsize alignment,
gsize memsize)
{
gpointer aligned_memory = NULL;
gint err = ENOMEM;
#if HAVE_COMPLIANT_POSIX_MEMALIGN
err = posix_memalign (&aligned_memory, alignment, memsize);
#elif HAVE_MEMALIGN
errno = 0;
aligned_memory = memalign (alignment, memsize);
err = errno;
#elif MOBILE_PORT
const guint n_pages = 2;
guint8 *mem = malloc (n_pages * sys_page_size);
err = errno;
if (mem)
{
guint8 *amem = (guint8*) ALIGN ((gsize) mem, sys_page_size);
guint16 offset = amem - mem;
guint16 *p = (guint16*)(amem + sys_page_size - NATIVE_MALLOC_PADDING);
*p = offset;
aligned_memory = amem;
}
#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 */
while (--i >= 0)
g_trash_stack_push (&compat_valloc_trash, amem + i * sys_page_size);
}
}
aligned_memory = g_trash_stack_pop (&compat_valloc_trash);
#endif
if (!aligned_memory)
errno = err;
return aligned_memory;
}
static void
allocator_memfree (gsize memsize,
gpointer mem)
{
#ifdef MOBILE_PORT
free (mem);
#elif (HAVE_COMPLIANT_POSIX_MEMALIGN) || (HAVE_MEMALIGN || HAVE_VALLOC)
free (mem);
#else
mem_assert (memsize <= sys_page_size);
g_trash_stack_push (&compat_valloc_trash, mem);
#endif
}
#include <stdio.h>
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();
fprintf (stderr, "%s[%u]: GSlice: ", pname ? pname : "", getpid());
va_start (args, format);
vfprintf (stderr, format, args);
va_end (args);
fputs ("\n", stderr);
_exit (1);
}
#define __G_SLICE_C__
#include "galiasdef.c"