static void *vm_malloc_pages(VM *vm, size_t len, size_t alignment, int dirty_ok)
{
char *r;
FreeBlock *blockfree = vm->freeblocks;
if (!page_size)
page_size = getpagesize();
/* Round up to nearest page: */
if (len & (page_size - 1))
len += page_size - (len & (page_size - 1));
/* Something from the cache, perhaps? */
r = alloc_cache_find_pages(blockfree, len, alignment, dirty_ok);
if(!r) {
/* attempt to allocate from OS */
r = os_vm_alloc_pages(len + alignment);
if(r == (void *)-1) { return NULL; }
if (alignment) {
/* We allocated too large so we can choose the alignment. */
size_t extra = alignment;
char *real_r = (char*)(((unsigned long)r + (alignment - 1)) & (~(alignment - 1)));
long pre_extra = real_r - r;
/* in front extra */
if (pre_extra) { os_vm_free_pages(r, pre_extra); }
/* in back extra exists */
if (pre_extra < extra) {
if (pre_extra == 0) {
/* Instead of actually unmapping, put it in the cache, and there's
a good chance we can use it next time: */
vm_memory_allocated_inc(vm, extra);
alloc_cache_return_mem(vm, real_r + len, extra, 1);
}
else { os_vm_free_pages(real_r + len, extra - pre_extra); }
}
r = real_r;
}
vm_memory_allocated_inc(vm, len);
}
return r;
}
static void *alloc_cache_alloc_page(AllocCacheBlock *blockfree, size_t len, size_t alignment, int dirty_ok, intptr_t *size_diff)
{
char *r;
/* Something from the cache, perhaps? */
r = alloc_cache_find_pages(blockfree, len, alignment, dirty_ok);
if(!r) {
/* attempt to allocate from OS */
size_t extra = (alignment ? (alignment + CACHE_SEED_PAGES * APAGE_SIZE) : 0);
r = os_alloc_pages(len + extra);
if(r == (void *)-1) { return NULL; }
if (alignment) {
/* We allocated too large so we can choose the alignment. */
char *real_r = (char*)(((uintptr_t)r + (alignment - 1)) & (~(alignment - 1)));
intptr_t pre_extra = real_r - r;
/* in front extra */
if (pre_extra) {
/* printf("FREEING FRONT %p %lx\n", r, pre_extra); */
os_free_pages(r, pre_extra); }
/* in back extra exists */
if (pre_extra < extra) {
if (pre_extra == 0) {
/* Instead of actually unmapping, put it in the cache, and there's
a good chance we can use it next time: */
(*size_diff) += extra;
(*size_diff) += alloc_cache_free_page(blockfree, real_r + len, extra, 1, 1);
} else {
os_free_pages(real_r + len, extra - pre_extra);
}
}
r = real_r;
}
(*size_diff) += len;
}
return r;
}
