growable buddy memory runtime

source/quickjs-internal.h

@@ -95,6 +95,9 @@
 /* test the GC by forcing it before each object allocation */
 // #define FORCE_GC_AT_MALLOC
 
+#include <sys/mman.h>
+#include <unistd.h>
+
 #define POISON_HEAP
 /* POISON_HEAP: Use ASan's memory poisoning to detect stale pointer access */
 #ifdef POISON_HEAP
@@ -116,9 +119,6 @@
 #define gc_unpoison_region(addr, size) ((void)0)
 #endif
 
-#include <sys/mman.h>
-#include <unistd.h>
-
 static inline size_t poison_page_align(size_t size) {
   size_t ps = (size_t)sysconf(_SC_PAGESIZE);
   return (size + ps - 1) & ~(ps - 1);
@@ -333,9 +333,8 @@ static inline objhdr_t objhdr_set_cap56 (objhdr_t h, uint64_t cap) {
 #else
   #define BUDDY_MIN_ORDER 9   /* 512B minimum on 32-bit */
 #endif
-#define BUDDY_MAX_ORDER 28 /* 256MB maximum */
-#define BUDDY_LEVELS (BUDDY_MAX_ORDER - BUDDY_MIN_ORDER + 1)
-#define BUDDY_POOL_SIZE (1ULL << BUDDY_MAX_ORDER)
+#define BUDDY_MAX_LEVELS 40   /* supports pools up to 2^(BUDDY_MIN_ORDER+39) */
+#define BUDDY_DEFAULT_POOL (1ULL << 24) /* 16MB initial pool */
 
 typedef struct BuddyBlock {
   struct BuddyBlock *next;
@@ -344,15 +343,26 @@ typedef struct BuddyBlock {
   uint8_t is_free;
 } BuddyBlock;
 
+typedef struct BuddyPool {
+  struct BuddyPool *next;
+  uint8_t *base;
+  size_t total_size;
+  uint8_t max_order;        /* log2(total_size) */
+  uint32_t alloc_count;     /* outstanding allocations */
+  BuddyBlock *free_lists[BUDDY_MAX_LEVELS];
+} BuddyPool;
+
 typedef struct BuddyAllocator {
-  uint8_t *base;     /* 256MB base address */
-  size_t total_size; /* 256MB */
-  BuddyBlock *free_lists[BUDDY_LEVELS];
-  uint8_t initialized;
+  BuddyPool *pools;         /* linked list, newest first */
+  size_t next_pool_size;    /* next pool doubles from this */
+  size_t initial_size;      /* starting pool size */
+  size_t cap;               /* 0 = no cap */
+  size_t total_mapped;      /* sum of all pool sizes */
 } BuddyAllocator;
 
 /* Forward declarations for buddy allocator functions */
 static void buddy_destroy (BuddyAllocator *b);
+static size_t buddy_max_block (BuddyAllocator *b);
 
 /* controls a host of contexts, handing out memory and scheduling */
 struct JSRuntime {