Memory allocation scheme for w32/w64:
- Buffers are mmap'ed using a very simple emulation of mmap/munmap
- - During the temacs phase, if unexec is to be used:
- * we use a private heap declared to be stored into the `dumped_data'
- * unfortunately, this heap cannot be made growable, so the size of
- blocks it can allocate is limited to (0x80000 - pagesize)
- * the blocks that are larger than this are allocated from the end
- of the `dumped_data' array; there are not so many of them.
- We use a very simple first-fit scheme to reuse those blocks.
- * we check that the private heap does not cross the area used
- by the bigger chunks.
- During the emacs phase, or always if pdumper is used:
* we create a private heap for new memory blocks
* we make sure that we never free a block that has been dumped.
SIZE_T Reserved[ 2 ];
} RTL_HEAP_PARAMETERS, *PRTL_HEAP_PARAMETERS;
-/* We reserve space for dumping emacs lisp byte-code inside a static
- array. By storing it in an array, the generic mechanism in
- unexecw32.c will be able to dump it without the need to add a
- special segment to the executable. In order to be able to do this
- without losing too much space, we need to create a Windows heap at
- the specific address of the static array. The RtlCreateHeap
- available inside the NT kernel since XP will do this. It allows the
- creation of a non-growable heap at a specific address. So before
- dumping, we create a non-growable heap at the address of the
- dumped_data[] array. After dumping, we reuse memory allocated
- there without being able to free it (but most of it is not meant to
- be freed anyway), and we use a new private heap for all new
- allocations. */
-
-/* FIXME: Most of the space reserved for dumped_data[] is only used by
- the 1st bootstrap-emacs.exe built while bootstrapping. Once the
- preloaded Lisp files are byte-compiled, the next loadup uses less
- than half of the size stated below. It would be nice to find a way
- to build only the first bootstrap-emacs.exe with the large size,
- and reset that to a lower value afterwards. */
-#ifndef HAVE_UNEXEC
-/* We don't use dumped_data[], so define to a small size that won't
- matter. */
-# define DUMPED_HEAP_SIZE 10
-#else
-# if defined _WIN64 || defined WIDE_EMACS_INT
-# define DUMPED_HEAP_SIZE (28*1024*1024)
-# else
-# define DUMPED_HEAP_SIZE (24*1024*1024)
-# endif
-#endif
-
-static unsigned char dumped_data[DUMPED_HEAP_SIZE];
-
/* Info for keeping track of our dynamic heap used after dumping. */
unsigned char *data_region_base = NULL;
unsigned char *data_region_end = NULL;
static DWORD blocks_number = 0;
static unsigned char *bc_limit;
-/* Handle for the private heap:
- - inside the dumped_data[] array before dump with unexec,
- - outside of it after dump, or always if pdumper is used.
-*/
-HANDLE heap = NULL;
-
/* We redirect the standard allocation functions. */
malloc_fn the_malloc_fn;
realloc_fn the_realloc_fn;
It would be if the memory was shared.
https://stackoverflow.com/questions/307060/what-is-the-purpose-of-allocating-pages-in-the-pagefile-with-createfilemapping */
-/* This is the function to commit memory when the heap allocator
- claims for new memory. Before dumping with unexec, we allocate
- space from the fixed size dumped_data[] array.
-*/
-static NTSTATUS NTAPI
-dumped_data_commit (PVOID Base, PVOID *CommitAddress, PSIZE_T CommitSize)
-{
- /* This is used before dumping.
-
- The private heap is stored at dumped_data[] address.
- We commit contiguous areas of the dumped_data array
- as requests arrive. */
- *CommitAddress = data_region_base + committed;
- committed += *CommitSize;
- /* Check that the private heap area does not overlap the big chunks area. */
- if (((unsigned char *)(*CommitAddress)) + *CommitSize >= bc_limit)
- {
- fprintf (stderr,
- "dumped_data_commit: memory exhausted.\nEnlarge dumped_data[]!\n");
- exit (-1);
- }
- return 0;
-}
-
/* Heap creation. */
/* We want to turn on Low Fragmentation Heap for XP and older systems.
#endif
void
-init_heap (bool use_dynamic_heap)
+init_heap (void)
{
- /* FIXME: Remove the condition, the 'else' branch below, and all the
- related definitions and code, including dumped_data[], when unexec
- support is removed from Emacs. */
- if (use_dynamic_heap)
- {
- /* After dumping, use a new private heap. We explicitly enable
- the low fragmentation heap (LFH) here, for the sake of pre
- Vista versions. Note: this will harmlessly fail on Vista and
- later, where the low-fragmentation heap is enabled by
- default. It will also fail on pre-Vista versions when Emacs
- is run under a debugger; set _NO_DEBUG_HEAP=1 in the
- environment before starting GDB to get low fragmentation heap
- on XP and older systems, for the price of losing "certain
- heap debug options"; for the details see
- https://msdn.microsoft.com/en-us/library/windows/desktop/aa366705%28v=vs.85%29.aspx. */
- data_region_end = data_region_base;
-
- /* Create the private heap. */
- heap = HeapCreate (0, 0, 0);
+ /* After dumping, use a new private heap. We explicitly enable
+ the low fragmentation heap (LFH) here, for the sake of pre
+ Vista versions. Note: this will harmlessly fail on Vista and
+ later, where the low-fragmentation heap is enabled by
+ default. It will also fail on pre-Vista versions when Emacs
+ is run under a debugger; set _NO_DEBUG_HEAP=1 in the
+ environment before starting GDB to get low fragmentation heap
+ on XP and older systems, for the price of losing "certain
+ heap debug options"; for the details see
+ https://msdn.microsoft.com/en-us/library/windows/desktop/aa366705%28v=vs.85%29.aspx. */
+ data_region_end = data_region_base;
+
+ /* Create the private heap. */
+ heap = HeapCreate (0, 0, 0);
#ifndef MINGW_W64
- unsigned long enable_lfh = 2;
- /* Set the low-fragmentation heap for OS before Vista. */
- HMODULE hm_kernel32dll = LoadLibrary ("kernel32.dll");
- HeapSetInformation_Proc s_pfn_Heap_Set_Information =
- (HeapSetInformation_Proc) get_proc_addr (hm_kernel32dll,
- "HeapSetInformation");
- if (s_pfn_Heap_Set_Information != NULL)
- {
- if (s_pfn_Heap_Set_Information ((PVOID) heap,
- HeapCompatibilityInformation,
- &enable_lfh, sizeof(enable_lfh)) == 0)
- DebPrint (("Enabling Low Fragmentation Heap failed: error %ld\n",
- GetLastError ()));
- }
+ unsigned long enable_lfh = 2;
+ /* Set the low-fragmentation heap for OS before Vista. */
+ HMODULE hm_kernel32dll = LoadLibrary ("kernel32.dll");
+ HeapSetInformation_Proc s_pfn_Heap_Set_Information =
+ (HeapSetInformation_Proc) get_proc_addr (hm_kernel32dll,
+ "HeapSetInformation");
+ if (s_pfn_Heap_Set_Information != NULL)
+ {
+ if (s_pfn_Heap_Set_Information ((PVOID) heap,
+ HeapCompatibilityInformation,
+ &enable_lfh, sizeof(enable_lfh)) == 0)
+ DebPrint (("Enabling Low Fragmentation Heap failed: error %ld\n",
+ GetLastError ()));
+ }
#endif
- if (os_subtype == OS_SUBTYPE_9X)
- {
- the_malloc_fn = malloc_after_dump_9x;
- the_realloc_fn = realloc_after_dump_9x;
- the_free_fn = free_after_dump_9x;
- }
- else
- {
- the_malloc_fn = malloc_after_dump;
- the_realloc_fn = realloc_after_dump;
- the_free_fn = free_after_dump;
- }
+ if (os_subtype == OS_SUBTYPE_9X)
+ {
+ the_malloc_fn = malloc_after_dump_9x;
+ the_realloc_fn = realloc_after_dump_9x;
+ the_free_fn = free_after_dump_9x;
}
- else /* Before dumping with unexec: use static heap. */
+ else
{
- /* Find the RtlCreateHeap function. Headers for this function
- are provided with the w32 DDK, but the function is available
- in ntdll.dll since XP. */
- HMODULE hm_ntdll = LoadLibrary ("ntdll.dll");
- RtlCreateHeap_Proc s_pfn_Rtl_Create_Heap
- = (RtlCreateHeap_Proc) get_proc_addr (hm_ntdll, "RtlCreateHeap");
- /* Specific parameters for the private heap. */
- RTL_HEAP_PARAMETERS params;
- ZeroMemory (¶ms, sizeof(params));
- params.Length = sizeof(RTL_HEAP_PARAMETERS);
-
- data_region_base = (unsigned char *)ROUND_UP (dumped_data, 0x1000);
- data_region_end = bc_limit = dumped_data + DUMPED_HEAP_SIZE;
-
- params.InitialCommit = committed = 0x1000;
- params.InitialReserve = sizeof(dumped_data);
- /* Use our own routine to commit memory from the dumped_data
- array. */
- params.CommitRoutine = &dumped_data_commit;
-
- /* Create the private heap. */
- if (s_pfn_Rtl_Create_Heap == NULL)
- {
- fprintf (stderr, "Cannot build Emacs without RtlCreateHeap being available; exiting.\n");
- exit (-1);
- }
- heap = s_pfn_Rtl_Create_Heap (0, data_region_base, 0, 0, NULL, ¶ms);
-
- if (os_subtype == OS_SUBTYPE_9X)
- {
- fprintf (stderr, "Cannot dump Emacs on Windows 9X; exiting.\n");
- exit (-1);
- }
- else
- {
- the_malloc_fn = malloc_before_dump;
- the_realloc_fn = realloc_before_dump;
- the_free_fn = free_before_dump;
- }
+ the_malloc_fn = malloc_after_dump;
+ the_realloc_fn = realloc_after_dump;
+ the_free_fn = free_after_dump;
}
/* Update system version information to match current system. */
projects / emacs.git / commitdiff