1 /* -----------------------------------------------------------------------------
2 * $Id: MBlock.c,v 1.42 2002/12/11 15:36:42 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 barf("out of memory (requested %d bytes)", size);
132 barf("getMBlock: mmap failed");
139 // Implements the general case: allocate a chunk of memory of 'size'
143 gen_map_mblocks (int size)
148 // Try to map a larger block, and take the aligned portion from
149 // it (unmap the rest).
151 ret = my_mmap(0, size);
153 // unmap the slop bits around the chunk we allocated
154 slop = (W_)ret & MBLOCK_MASK;
156 if (munmap(ret, MBLOCK_SIZE - slop) == -1) {
157 barf("gen_map_mblocks: munmap failed");
159 if (slop > 0 && munmap(ret+size-slop, slop) == -1) {
160 barf("gen_map_mblocks: munmap failed");
163 // ToDo: if we happened to get an aligned block, then don't
164 // unmap the excess, just use it.
166 // next time, try after the block we just got.
167 ret += MBLOCK_SIZE - slop;
172 // The external interface: allocate 'n' mblocks, and return the
178 static caddr_t next_request = (caddr_t)HEAP_BASE;
180 lnat size = MBLOCK_SIZE * n;
183 if (next_request == 0) {
184 // use gen_map_mblocks the first time.
185 ret = gen_map_mblocks(size);
187 ret = my_mmap(next_request, size);
189 if (((W_)ret & MBLOCK_MASK) != 0) {
191 #if 0 // defined(DEBUG)
192 belch("warning: getMBlock: misaligned block %p returned when allocating %d megablock(s) at %p", ret, n, next_request);
195 // unmap this block...
196 if (munmap(ret, size) == -1) {
197 barf("getMBlock: munmap failed");
199 // and do it the hard way
200 ret = gen_map_mblocks(size);
204 // Next time, we'll try to allocate right after the block we just got.
205 // ToDo: check that we haven't already grabbed the memory at next_request
206 next_request = ret + size;
208 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at %p\n",n,ret));
211 for (i = 0; i < n; i++) {
212 MARK_HEAP_ALLOCED( ret + i * MBLOCK_SIZE );
215 mblocks_allocated += n;
220 #else /* defined(mingw32_TARGET_OS) || defined(cygwin32_TARGET_OS) */
223 On Win32 platforms we make use of the two-phased virtual memory API
224 to allocate mega blocks. We proceed as follows:
226 Reserve a large chunk of VM (256M at the time, or what the user asked
227 for via the -M option), but don't supply a base address that's aligned on
228 a MB boundary. Instead we round up to the nearest mblock from the chunk of
229 VM we're handed back from the OS (at the moment we just leave the 'slop' at
230 the beginning of the reserved chunk unused - ToDo: reuse it .)
232 Reserving memory doesn't allocate physical storage (not even in the
233 page file), this is done later on by committing pages (or mega-blocks in
237 char* base_non_committed = (char*)0;
238 char* end_non_committed = (char*)0;
240 /* Default is to reserve 256M of VM to minimise the slop cost. */
241 #define SIZE_RESERVED_POOL ( 256 * 1024 * 1024 )
243 /* Number of bytes reserved */
244 static unsigned long size_reserved_pool = SIZE_RESERVED_POOL;
249 static char* base_mblocks = (char*)0;
250 static char* next_request = (char*)0;
251 void* ret = (void*)0;
254 lnat size = MBLOCK_SIZE * n;
256 if ( (base_non_committed == 0) || (next_request + size > end_non_committed) ) {
257 if (base_non_committed) {
258 barf("RTS exhausted max heap size (%d bytes)\n", size_reserved_pool);
260 if (RtsFlags.GcFlags.maxHeapSize != 0) {
261 size_reserved_pool = BLOCK_SIZE * RtsFlags.GcFlags.maxHeapSize;
262 if (size_reserved_pool < MBLOCK_SIZE) {
263 size_reserved_pool = 2*MBLOCK_SIZE;
266 base_non_committed = VirtualAlloc ( NULL
271 if ( base_non_committed == 0 ) {
272 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
275 end_non_committed = (char*)base_non_committed + (unsigned long)size_reserved_pool;
276 /* The returned pointer is not aligned on a mega-block boundary. Make it. */
277 base_mblocks = (char*)((unsigned long)base_non_committed & (unsigned long)~MBLOCK_MASK) + MBLOCK_SIZE;
279 fprintf(stderr, "getMBlocks: Dropping %d bytes off of 256M chunk\n",
280 (unsigned)base_mblocks - (unsigned)base_non_committed);
283 if ( ((char*)base_mblocks + size) > end_non_committed ) {
284 fprintf(stderr, "getMBlocks: oops, committed too small a region to start with.");
287 next_request = base_mblocks;
291 /* Commit the mega block(s) to phys mem */
292 if ( ret != (void*)-1 ) {
293 ret = VirtualAlloc(next_request, size, MEM_COMMIT, PAGE_READWRITE);
295 fprintf(stderr, "getMBlocks: VirtualAlloc failed with: %ld\n", GetLastError());
300 if (((W_)ret & MBLOCK_MASK) != 0) {
301 barf("getMBlocks: misaligned block returned");
304 if (ret == (void*)-1) {
305 barf("getMBlocks: unknown memory allocation failure on Win32.");
308 IF_DEBUG(gc,fprintf(stderr,"Allocated %d megablock(s) at 0x%x\n",n,(nat)ret));
309 next_request = (char*)next_request + size;
311 mblocks_allocated += n;
314 for (i = 0; i < n; i++) {
315 MARK_HEAP_ALLOCED ( ret + i * MBLOCK_SIZE );
321 /* Hand back the physical memory that is allocated to a mega-block.
322 ToDo: chain the released mega block onto some list so that
323 getMBlocks() can get at it.
329 freeMBlock(void* p, nat n)
333 rc = VirtualFree(p, n * MBLOCK_SIZE , MEM_DECOMMIT );
337 fprintf(stderr, "freeMBlocks: VirtualFree failed with: %d\n", GetLastError());