Add lazy commit option

src/base/arena.c

@@ -10,7 +10,7 @@ static MemoryBlock *memoryblock_allocate(U32 size, U32 commit_size, U32 page_siz
 
     MemoryBlock *block = memory_reserve(size);
     Assert(block != NULL);
-    memory_commit(block, commit_size);
+    memory_commit(block, commit_size, false);
 
     ASAN_POISON_MEMORY_REGION(block, size);
     ASAN_UNPOISON_MEMORY_REGION(block, MemoryBlock_Header_Size);
@@ -38,7 +38,7 @@ void arena_init(Arena *arena, const ArenaOptions *opts)
     MemoryBlock *block  = memoryblock_allocate(aligned_size, aligned_commit_size, page_size);
 
     arena->flags            = opts->flags;
-    arena->temp_level = 0;
+    arena->temp_level       = 0;
     arena->current          = block;
     arena->block_size       = aligned_size;
     arena->commit_size      = aligned_commit_size;
@@ -61,7 +61,6 @@ void *arena_push(Arena *arena, U32 size, U32 align)
 {
     Assert(IsPow2(align));
 
-
     MemoryBlock *block = arena->current;
     U32 start_pos = AlignUp(block->first_free, align);  // might align past block->size, handled in below check
     U32 available = block->size - start_pos;
@@ -97,7 +96,7 @@ void *arena_push(Arena *arena, U32 size, U32 align)
         U32 aligned_size      = RoundUpToMultiple(aligned_end_pos - block->committed_end, arena->commit_size);
         aligned_size = Min(aligned_size, block->size - block->committed_end);
 
-        memory_commit(&block->base[block->committed_end], aligned_size);
+        memory_commit(&block->base[block->committed_end], aligned_size, false);
         block->committed_end  += aligned_size;
         Assert(block->committed_end <= block->size);
     }

src/base/arena.h

@@ -89,7 +89,7 @@ static INLINE void *arena_allocator_func(Allocator *allocator, AllocOperation op
             return NULL;
     }
 
-    Assert(false);
+    ShouldNotHappen;
 }
 
 static INLINE Allocator arena_allocator(Arena *arena)

src/base/platform.c

@@ -91,7 +91,7 @@ void *memory_reserve(size_t size)
     return mem;
 }
 
-void memory_commit(void *mem, size_t size)
+void memory_commit(void *mem, size_t size, bool lazy)
 {
     Assert(IsPageAligned((UMM)mem));
     Assert(IsPageAligned(size));
@@ -100,7 +100,11 @@ void memory_commit(void *mem, size_t size)
     int rc;
     rc = mprotect(mem, size, PROT_READ | PROT_WRITE);
     Assert(rc == 0);
-    rc = madvise(mem, size, MADV_WILLNEED);
+    if (lazy) {
+        rc = madvise(mem, size, MADV_POPULATE_WRITE);
+    } else {
+        rc = madvise(mem, size, MADV_WILLNEED);
+    }
     Assert(rc == 0);
 }
 

src/base/platform.h

@@ -11,6 +11,7 @@ U32 platform_page_size(void);
 // Memory functions expect mem and size to be page aligned
 void *memory_allocate_and_commit(size_t size);
 void *memory_reserve(size_t size);
-void memory_commit(void *mem, size_t size);
+
+void memory_commit(void *mem, size_t size, bool lazy);
 void memory_decommit(void *mem, size_t size);
 void memory_free(void *mem, size_t size);

src/main.c

@@ -8,10 +8,14 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#define ARENA_DEBUG 1
 
 void arena_dump(const Arena *arena)
 {
-    return;
+    if (!ARENA_DEBUG) {
+        return;
+    }
+
     MemoryBlock *block = arena->current;
     puts("@@@@@@@@@@");
     while (block) {
@@ -19,7 +23,7 @@ void arena_dump(const Arena *arena)
         printf("base:        %p\n", block->base);
         printf("size:        %u\n", block->size);
         printf("first_free:         %u\n", block->first_free);
-        printf("total_used:    %lu\n",block->arena_offset);
+        printf("arena_offset:    %lu\n",block->arena_offset);
         printf("prev: %p\n", block->prev);
         puts("-----Arena  end-");
         block = block->prev;
@@ -166,6 +170,28 @@ static void arena_test_4(void)
     arena_free(&arena);
 }
 
+static void arena_test_bigger_push(void)
+{
+    TRACEF("\n\n");
+    ArenaOptions arena_params = {};
+    U32 arena_size = KB(256) + MemoryBlock_Header_Size;
+    U32 commit_size = KB(8);
+    arena_params.size = arena_size;
+    arena_params.commit_size = commit_size;
+    Arena arena;
+    arena_init(&arena, &arena_params);
+    arena_dump(&arena);
+    void *ptr = arena_push(&arena, KB(256), 1);
+    MemoryZero(ptr, 512);
+    printf("Allocated ptr %p\n", ptr);
+    arena_dump(&arena);
+    ptr = arena_push(&arena, MB(4), 4);
+    MemoryZero(ptr, MB(4));
+    printf("Allocated ptr %p\n", ptr);
+    arena_dump(&arena);
+    arena_free(&arena);
+}
+
 static void arena_test_allocator_interface(void)
 {
     TRACEF("\n\n");
@@ -741,6 +767,7 @@ int main(int argc, char *argv[])
     arena_test_4();
     arena_test_decommit();
     arena_test_allocator_interface();
+    arena_test_bigger_push();
     miniarena_test1();
     apool_test();
     apool_test_autogrow();