1 /* -----------------------------------------------------------------------------
2 * $Id: MBlock.c,v 1.44 2003/03/26 02:12:38 sof 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. For this to work, you
166 // need to keep in mind the following:
167 // * Calling my_mmap() with an 'addr' arg pointing to
168 // already my_mmap()ed space is OK and won't fail.
169 // * If my_mmap() can't satisfy the request at the
170 // given 'next_request' address in getMBlocks(), that
171 // you unmap the extra mblock mmap()ed here (or simply
172 // satisfy yourself that the slop introduced isn't worth
176 // next time, try after the block we just got.
177 ret += MBLOCK_SIZE - slop;
182 // The external interface: allocate 'n' mblocks, and return the
188 static caddr_t next_request = (caddr_t)HEAP_BASE;
190 lnat size = MBLOCK_SIZE * n;
193 if (next_request == 0) {
194 // use gen_map_mblocks the first time.
195 ret = gen_map_mblocks(size);
197 ret = my_mmap(next_request, size);
199 if (((W_)ret & MBLOCK_MASK) != 0) {
201 #if 0 // defined(DEBUG)
202 belch("warning: getMBlock: misaligned block %p returned when allocating %d megablock(s) at %p", ret, n, next_request);
205 // unmap this block...
206 if (munmap(ret, size) == -1) {
207 barf("getMBlock: munmap failed");
209 // and do it the hard way
210 ret = gen_map_mblocks(size);
214 // Next time, we'll try to allocate right after the block we just got.
215 // ToDo: check that we haven't already grabbed the memory at next_request
216 next_request = ret + size;
218 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at %p\n",n,ret));
221 for (i = 0; i < n; i++) {
222 MARK_HEAP_ALLOCED( ret + i * MBLOCK_SIZE );
225 mblocks_allocated += n;
230 #else /* defined(mingw32_TARGET_OS) || defined(cygwin32_TARGET_OS) */
233 On Win32 platforms we make use of the two-phased virtual memory API
234 to allocate mega blocks. We proceed as follows:
236 Reserve a large chunk of VM (256M at the time, or what the user asked
237 for via the -M option), but don't supply a base address that's aligned on
238 a MB boundary. Instead we round up to the nearest mblock from the chunk of
239 VM we're handed back from the OS (at the moment we just leave the 'slop' at
240 the beginning of the reserved chunk unused - ToDo: reuse it .)
242 Reserving memory doesn't allocate physical storage (not even in the
243 page file), this is done later on by committing pages (or mega-blocks in
247 char* base_non_committed = (char*)0;
248 char* end_non_committed = (char*)0;
250 /* Default is to reserve 256M of VM to minimise the slop cost. */
251 #define SIZE_RESERVED_POOL ( 256 * 1024 * 1024 )
253 /* Number of bytes reserved */
254 static unsigned long size_reserved_pool = SIZE_RESERVED_POOL;
259 static char* base_mblocks = (char*)0;
260 static char* next_request = (char*)0;
261 void* ret = (void*)0;
264 lnat size = MBLOCK_SIZE * n;
266 if ( (base_non_committed == 0) || (next_request + size > end_non_committed) ) {
267 if (base_non_committed) {
268 barf("RTS exhausted max heap size (%d bytes)\n", size_reserved_pool);
270 if (RtsFlags.GcFlags.maxHeapSize != 0) {
271 size_reserved_pool = BLOCK_SIZE * RtsFlags.GcFlags.maxHeapSize;
272 if (size_reserved_pool < MBLOCK_SIZE) {
273 size_reserved_pool = 2*MBLOCK_SIZE;
276 base_non_committed = VirtualAlloc ( NULL
281 if ( base_non_committed == 0 ) {
282 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
285 end_non_committed = (char*)base_non_committed + (unsigned long)size_reserved_pool;
286 /* The returned pointer is not aligned on a mega-block boundary. Make it. */
287 base_mblocks = (char*)((unsigned long)base_non_committed & (unsigned long)~MBLOCK_MASK) + MBLOCK_SIZE;
289 fprintf(stderr, "getMBlocks: Dropping %d bytes off of 256M chunk\n",
290 (unsigned)base_mblocks - (unsigned)base_non_committed);
293 if ( ((char*)base_mblocks + size) > end_non_committed ) {
294 fprintf(stderr, "getMBlocks: oops, committed too small a region to start with.");
297 next_request = base_mblocks;
301 /* Commit the mega block(s) to phys mem */
302 if ( ret != (void*)-1 ) {
303 ret = VirtualAlloc(next_request, size, MEM_COMMIT, PAGE_READWRITE);
305 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
310 if (((W_)ret & MBLOCK_MASK) != 0) {
311 barf("getMBlocks: misaligned block returned");
314 if (ret == (void*)-1) {
315 barf("getMBlocks: unknown memory allocation failure on Win32.");
318 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at 0x%x\n",n,(nat)ret));
319 next_request = (char*)next_request + size;
321 mblocks_allocated += n;
324 for (i = 0; i < n; i++) {
325 MARK_HEAP_ALLOCED ( ret + i * MBLOCK_SIZE );
331 /* Hand back the physical memory that is allocated to a mega-block.
332 ToDo: chain the released mega block onto some list so that
333 getMBlocks() can get at it.
339 freeMBlock(void* p, nat n)
343 rc = VirtualFree(p, n * MBLOCK_SIZE , MEM_DECOMMIT );
347 fprintf(stderr, "freeMBlocks: VirtualFree failed with: %d\n", GetLastError());