1 /* -----------------------------------------------------------------------------
2 * $Id: MBlock.c,v 1.35 2002/11/05 09:26:04 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 StgWord8 mblock_map[4096]; // initially all zeros
56 mblockIsHeap (void *p)
58 mblock_map[((StgWord)p & ~MBLOCK_MASK) >> MBLOCK_SHIFT] = 1;
61 /* -----------------------------------------------------------------------------
62 Allocate new mblock(s)
63 -------------------------------------------------------------------------- */
71 /* -----------------------------------------------------------------------------
74 On Unix-like systems, we use mmap() to allocate our memory. We
75 want memory in chunks of MBLOCK_SIZE, and aligned on an MBLOCK_SIZE
76 boundary. The mmap() interface doesn't give us this level of
77 control, so we have to use some heuristics.
79 In the general case, if we want a block of n megablocks, then we
80 allocate n+1 and trim off the slop from either side (using
81 munmap()) to get an aligned chunk of size n. However, the next
82 time we'll try to allocate directly after the previously allocated
83 chunk, on the grounds that this is aligned and likely to be free.
84 If it turns out that we were wrong, we have to munmap() and try
85 again using the general method.
86 -------------------------------------------------------------------------- */
88 #if !defined(mingw32_TARGET_OS) && !defined(cygwin32_TARGET_OS)
90 // A wrapper around mmap(), to abstract away from OS differences in
91 // the mmap() interface.
94 my_mmap (void *addr, int size)
98 #ifdef solaris2_TARGET_OS
100 int fd = open("/dev/zero",O_RDONLY);
101 ret = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
105 ret = mmap(addr, size, PROT_READ | PROT_WRITE,
106 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
107 #elif darwin_TARGET_OS
108 // Without MAP_FIXED, Apple's mmap ignores addr.
109 // With MAP_FIXED, it overwrites already mapped regions, whic
110 // mmap(0, ... MAP_FIXED ...) is worst of all: It unmaps the program text
111 // and replaces it with zeroes, causing instant death.
112 // This behaviour seems to be conformant with IEEE Std 1003.1-2001.
113 // Let's just use the underlying Mach Microkernel calls directly,
114 // they're much nicer.
118 if(addr) // try to allocate at adress
119 err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, FALSE);
120 if(!addr || err) // try to allocate anywhere
121 err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, TRUE);
126 vm_protect(mach_task_self(),ret,size,FALSE,VM_PROT_READ|VM_PROT_WRITE);
128 ret = mmap(addr, size, PROT_READ | PROT_WRITE,
129 MAP_ANON | MAP_PRIVATE, -1, 0);
135 // Implements the general case: allocate a chunk of memory of 'size'
139 gen_map_mblocks (int size)
144 // Try to map a larger block, and take the aligned portion from
145 // it (unmap the rest).
147 ret = my_mmap(0, size);
148 if (ret == (void *)-1) {
149 barf("gen_map_mblocks: mmap failed");
152 // unmap the slop bits around the chunk we allocated
153 slop = (W_)ret & MBLOCK_MASK;
155 if (munmap(ret, MBLOCK_SIZE - slop) == -1) {
156 barf("gen_map_mblocks: munmap failed");
158 if (slop > 0 && munmap(ret+size-slop, slop) == -1) {
159 barf("gen_map_mblocks: munmap failed");
162 // next time, try after the block we just got.
163 ret += MBLOCK_SIZE - slop;
168 // The external interface: allocate 'n' mblocks, and return the
174 static caddr_t next_request = (caddr_t)HEAP_BASE;
176 lnat size = MBLOCK_SIZE * n;
179 if (next_request == 0) {
180 // use gen_map_mblocks the first time.
181 ret = gen_map_mblocks(size);
183 ret = my_mmap(next_request, size);
185 if (ret == (void *)-1) {
186 if (errno == ENOMEM) {
187 barf("out of memory (requested %d bytes)", n * MBLOCK_SIZE);
189 barf("getMBlock: mmap failed");
193 if (((W_)ret & MBLOCK_MASK) != 0) {
196 belch("getMBlock: misaligned block %p returned when allocating %d megablock(s) at %p", ret, n, next_request);
199 // unmap this block...
200 if (munmap(ret, size) == -1) {
201 barf("getMBlock: munmap failed");
203 // and do it the hard way
204 ret = gen_map_mblocks(size);
208 // Next time, we'll try to allocate right after the block we just got.
209 next_request = ret + size;
211 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at %p\n",n,ret));
214 for (i = 0; i < n; i++) {
215 mblockIsHeap( ret + i * MBLOCK_SIZE );
218 mblocks_allocated += n;
223 #else /* defined(mingw32_TARGET_OS) || defined(cygwin32_TARGET_OS) */
226 On Win32 platforms we make use of the two-phased virtual memory API
227 to allocate mega blocks. We proceed as follows:
229 Reserve a large chunk of VM (256M at the time, or what the user asked
230 for via the -M option), but don't supply a base address that's aligned on
231 a MB boundary. Instead we round up to the nearest mblock from the chunk of
232 VM we're handed back from the OS (at the moment we just leave the 'slop' at
233 the beginning of the reserved chunk unused - ToDo: reuse it .)
235 Reserving memory doesn't allocate physical storage (not even in the
236 page file), this is done later on by committing pages (or mega-blocks in
240 char* base_non_committed = (char*)0;
241 char* end_non_committed = (char*)0;
243 /* Default is to reserve 256M of VM to minimise the slop cost. */
244 #define SIZE_RESERVED_POOL ( 256 * 1024 * 1024 )
246 /* Number of bytes reserved */
247 static unsigned long size_reserved_pool = SIZE_RESERVED_POOL;
252 static char* base_mblocks = (char*)0;
253 static char* next_request = (char*)0;
254 void* ret = (void*)0;
257 lnat size = MBLOCK_SIZE * n;
259 if ( (base_non_committed == 0) || (next_request + size > end_non_committed) ) {
260 if (base_non_committed) {
261 barf("RTS exhausted max heap size (%d bytes)\n", size_reserved_pool);
263 if (RtsFlags.GcFlags.maxHeapSize != 0) {
264 size_reserved_pool = BLOCK_SIZE * RtsFlags.GcFlags.maxHeapSize;
265 if (size_reserved_pool < MBLOCK_SIZE) {
266 size_reserved_pool = 2*MBLOCK_SIZE;
269 base_non_committed = VirtualAlloc ( NULL
274 if ( base_non_committed == 0 ) {
275 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
278 end_non_committed = (char*)base_non_committed + (unsigned long)size_reserved_pool;
279 /* The returned pointer is not aligned on a mega-block boundary. Make it. */
280 base_mblocks = (char*)((unsigned long)base_non_committed & (unsigned long)~MBLOCK_MASK) + MBLOCK_SIZE;
282 fprintf(stderr, "getMBlocks: Dropping %d bytes off of 256M chunk\n",
283 (unsigned)base_mblocks - (unsigned)base_non_committed);
286 if ( ((char*)base_mblocks + size) > end_non_committed ) {
287 fprintf(stderr, "getMBlocks: oops, committed too small a region to start with.");
290 next_request = base_mblocks;
294 /* Commit the mega block(s) to phys mem */
295 if ( ret != (void*)-1 ) {
296 ret = VirtualAlloc(next_request, size, MEM_COMMIT, PAGE_READWRITE);
298 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
303 if (((W_)ret & MBLOCK_MASK) != 0) {
304 barf("getMBlocks: misaligned block returned");
307 if (ret == (void*)-1) {
308 barf("getMBlocks: unknown memory allocation failure on Win32.");
311 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at 0x%x\n",n,(nat)ret));
312 next_request = (char*)next_request + size;
314 mblocks_allocated += n;
317 for (i = 0; i < n; i++) {
318 mblockIsHeap( ret + i * MBLOCK_SIZE );
324 /* Hand back the physical memory that is allocated to a mega-block.
325 ToDo: chain the released mega block onto some list so that
326 getMBlocks() can get at it.
332 freeMBlock(void* p, nat n)
336 rc = VirtualFree(p, n * MBLOCK_SIZE , MEM_DECOMMIT );
340 fprintf(stderr, "freeMBlocks: VirtualFree failed with: %d\n", GetLastError());