1 /* -----------------------------------------------------------------------------
2 * $Id: MBlock.c,v 1.43 2003/03/20 15:43:31 simonmar Exp $
4 * (c) The GHC Team 1998-1999
6 * MegaBlock Allocator Interface. This file contains all the dirty
7 * architecture-dependent hackery required to get a chunk of aligned
8 * memory from the operating system.
10 * ---------------------------------------------------------------------------*/
12 /* This is non-posix compliant. */
13 /* #include "PosixSource.h" */
19 #include "BlockAlloc.h"
27 #ifdef HAVE_SYS_TYPES_H
28 #include <sys/types.h>
30 #ifndef mingw32_TARGET_OS
31 # ifdef HAVE_SYS_MMAN_H
32 # include <sys/mman.h>
42 #include <mach/vm_map.h>
47 lnat mblocks_allocated = 0;
49 /* -----------------------------------------------------------------------------
50 The MBlock Map: provides our implementation of HEAP_ALLOCED()
51 -------------------------------------------------------------------------- */
53 #ifdef MBLOCK_MAP_SIZE
54 StgWord8 mblock_map[MBLOCK_MAP_SIZE]; // initially all zeros
57 /* -----------------------------------------------------------------------------
58 Allocate new mblock(s)
59 -------------------------------------------------------------------------- */
67 /* -----------------------------------------------------------------------------
70 On Unix-like systems, we use mmap() to allocate our memory. We
71 want memory in chunks of MBLOCK_SIZE, and aligned on an MBLOCK_SIZE
72 boundary. The mmap() interface doesn't give us this level of
73 control, so we have to use some heuristics.
75 In the general case, if we want a block of n megablocks, then we
76 allocate n+1 and trim off the slop from either side (using
77 munmap()) to get an aligned chunk of size n. However, the next
78 time we'll try to allocate directly after the previously allocated
79 chunk, on the grounds that this is aligned and likely to be free.
80 If it turns out that we were wrong, we have to munmap() and try
81 again using the general method.
82 -------------------------------------------------------------------------- */
84 #if !defined(mingw32_TARGET_OS) && !defined(cygwin32_TARGET_OS)
86 // A wrapper around mmap(), to abstract away from OS differences in
87 // the mmap() interface.
90 my_mmap (void *addr, int size)
94 #ifdef solaris2_TARGET_OS
96 int fd = open("/dev/zero",O_RDONLY);
97 ret = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
101 ret = mmap(addr, size, PROT_READ | PROT_WRITE,
102 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
103 #elif darwin_TARGET_OS
104 // Without MAP_FIXED, Apple's mmap ignores addr.
105 // With MAP_FIXED, it overwrites already mapped regions, whic
106 // mmap(0, ... MAP_FIXED ...) is worst of all: It unmaps the program text
107 // and replaces it with zeroes, causing instant death.
108 // This behaviour seems to be conformant with IEEE Std 1003.1-2001.
109 // Let's just use the underlying Mach Microkernel calls directly,
110 // they're much nicer.
114 if(addr) // try to allocate at adress
115 err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, FALSE);
116 if(!addr || err) // try to allocate anywhere
117 err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, TRUE);
119 if(err) // don't know what the error codes mean exactly
120 barf("memory allocation failed (requested %d bytes)", size);
122 vm_protect(mach_task_self(),ret,size,FALSE,VM_PROT_READ|VM_PROT_WRITE);
124 ret = mmap(addr, size, PROT_READ | PROT_WRITE | PROT_EXEC,
125 MAP_ANON | MAP_PRIVATE, -1, 0);
128 if (ret == (void *)-1) {
129 if (errno == ENOMEM) {
130 prog_belch("out of memory (requested %d bytes)", size);
131 stg_exit(EXIT_FAILURE);
133 barf("getMBlock: mmap failed");
140 // Implements the general case: allocate a chunk of memory of 'size'
144 gen_map_mblocks (int size)
149 // Try to map a larger block, and take the aligned portion from
150 // it (unmap the rest).
152 ret = my_mmap(0, size);
154 // unmap the slop bits around the chunk we allocated
155 slop = (W_)ret & MBLOCK_MASK;
157 if (munmap(ret, MBLOCK_SIZE - slop) == -1) {
158 barf("gen_map_mblocks: munmap failed");
160 if (slop > 0 && munmap(ret+size-slop, slop) == -1) {
161 barf("gen_map_mblocks: munmap failed");
164 // ToDo: if we happened to get an aligned block, then don't
165 // unmap the excess, just use it.
167 // next time, try after the block we just got.
168 ret += MBLOCK_SIZE - slop;
173 // The external interface: allocate 'n' mblocks, and return the
179 static caddr_t next_request = (caddr_t)HEAP_BASE;
181 lnat size = MBLOCK_SIZE * n;
184 if (next_request == 0) {
185 // use gen_map_mblocks the first time.
186 ret = gen_map_mblocks(size);
188 ret = my_mmap(next_request, size);
190 if (((W_)ret & MBLOCK_MASK) != 0) {
192 #if 0 // defined(DEBUG)
193 belch("warning: getMBlock: misaligned block %p returned when allocating %d megablock(s) at %p", ret, n, next_request);
196 // unmap this block...
197 if (munmap(ret, size) == -1) {
198 barf("getMBlock: munmap failed");
200 // and do it the hard way
201 ret = gen_map_mblocks(size);
205 // Next time, we'll try to allocate right after the block we just got.
206 // ToDo: check that we haven't already grabbed the memory at next_request
207 next_request = ret + size;
209 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at %p\n",n,ret));
212 for (i = 0; i < n; i++) {
213 MARK_HEAP_ALLOCED( ret + i * MBLOCK_SIZE );
216 mblocks_allocated += n;
221 #else /* defined(mingw32_TARGET_OS) || defined(cygwin32_TARGET_OS) */
224 On Win32 platforms we make use of the two-phased virtual memory API
225 to allocate mega blocks. We proceed as follows:
227 Reserve a large chunk of VM (256M at the time, or what the user asked
228 for via the -M option), but don't supply a base address that's aligned on
229 a MB boundary. Instead we round up to the nearest mblock from the chunk of
230 VM we're handed back from the OS (at the moment we just leave the 'slop' at
231 the beginning of the reserved chunk unused - ToDo: reuse it .)
233 Reserving memory doesn't allocate physical storage (not even in the
234 page file), this is done later on by committing pages (or mega-blocks in
238 char* base_non_committed = (char*)0;
239 char* end_non_committed = (char*)0;
241 /* Default is to reserve 256M of VM to minimise the slop cost. */
242 #define SIZE_RESERVED_POOL ( 256 * 1024 * 1024 )
244 /* Number of bytes reserved */
245 static unsigned long size_reserved_pool = SIZE_RESERVED_POOL;
250 static char* base_mblocks = (char*)0;
251 static char* next_request = (char*)0;
252 void* ret = (void*)0;
255 lnat size = MBLOCK_SIZE * n;
257 if ( (base_non_committed == 0) || (next_request + size > end_non_committed) ) {
258 if (base_non_committed) {
259 barf("RTS exhausted max heap size (%d bytes)\n", size_reserved_pool);
261 if (RtsFlags.GcFlags.maxHeapSize != 0) {
262 size_reserved_pool = BLOCK_SIZE * RtsFlags.GcFlags.maxHeapSize;
263 if (size_reserved_pool < MBLOCK_SIZE) {
264 size_reserved_pool = 2*MBLOCK_SIZE;
267 base_non_committed = VirtualAlloc ( NULL
272 if ( base_non_committed == 0 ) {
273 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
276 end_non_committed = (char*)base_non_committed + (unsigned long)size_reserved_pool;
277 /* The returned pointer is not aligned on a mega-block boundary. Make it. */
278 base_mblocks = (char*)((unsigned long)base_non_committed & (unsigned long)~MBLOCK_MASK) + MBLOCK_SIZE;
280 fprintf(stderr, "getMBlocks: Dropping %d bytes off of 256M chunk\n",
281 (unsigned)base_mblocks - (unsigned)base_non_committed);
284 if ( ((char*)base_mblocks + size) > end_non_committed ) {
285 fprintf(stderr, "getMBlocks: oops, committed too small a region to start with.");
288 next_request = base_mblocks;
292 /* Commit the mega block(s) to phys mem */
293 if ( ret != (void*)-1 ) {
294 ret = VirtualAlloc(next_request, size, MEM_COMMIT, PAGE_READWRITE);
296 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
301 if (((W_)ret & MBLOCK_MASK) != 0) {
302 barf("getMBlocks: misaligned block returned");
305 if (ret == (void*)-1) {
306 barf("getMBlocks: unknown memory allocation failure on Win32.");
309 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at 0x%x\n",n,(nat)ret));
310 next_request = (char*)next_request + size;
312 mblocks_allocated += n;
315 for (i = 0; i < n; i++) {
316 MARK_HEAP_ALLOCED ( ret + i * MBLOCK_SIZE );
322 /* Hand back the physical memory that is allocated to a mega-block.
323 ToDo: chain the released mega block onto some list so that
324 getMBlocks() can get at it.
330 freeMBlock(void* p, nat n)
334 rc = VirtualFree(p, n * MBLOCK_SIZE , MEM_DECOMMIT );
338 fprintf(stderr, "freeMBlocks: VirtualFree failed with: %d\n", GetLastError());