优化内存管理模块中raw allocator的内存利用效率

src/include/kernel/memm/allocator/raw.h

@@ -11,17 +11,25 @@ typedef struct __raw_allocator_cell
     usize length;   // 是实际使用的长度
     u8 content[0];
 } raw_allocator_cell;
+#define raw_allocator_next_cell(cell) (raw_allocator_cell *)((void *)((cell)->content) + (cell)->capacity)
 
 // 原始分配器
-// 包括至少一个cell，分配时像cell的分裂一样将空白的一段分成两段
-// 释放时，只把length归零，并不将cell合并
+//
+// 包括至少一个cell，分配时像cell的分裂一样将空白的一段分成两段，
+// 释放时，只把length归零，并不将cell合并。
 // length=0的cell称为空cell
-// 在分配时遇到第一个空cell时将紧随其后的空cell都合并掉
+//
+// 统计从上次细胞合并以来free的调用次数，当调用次数很多或可用空间不足时
+// 触发细胞合并。
 typedef struct __raw_allocator_t
 {
-    usize size, reserved;
+    usize size;
+    usize free_count; // free调用计数
+#define RAW_ALLOCATOR_FREE_MAX 64
+    usize rest_memory;
     raw_allocator_cell cells[0];
 } raw_allocator_t;
+#define raw_allocator_end(allocator) ((void *)(allocator) + (allocator)->size)
 
 void raw_allocator_new(raw_allocator_t *allocator, usize size);
 

src/kernel/main.c

@@ -43,7 +43,9 @@ void kmain(void *mb2_bootinfo)
     tty *tty0 = tty_new(tty_type_raw_framebuffer, tty_mode_text);
     tty_set_framebuffer(tty0, &fb);
 
-    tty_text_print(tty0, "Hello Metaverse!\n", gen_color(0xee, 0xee, 0xee), gen_color(0, 0, 0));
+    tty_text_print(tty0, "Hello ", gen_color(0xee, 0xee, 0xee), gen_color(0, 0, 0));
+    tty_text_print(tty0, "Metaverse", gen_color(0x0a, 0xee, 0x0a), gen_color(0, 0, 0));
+    tty_text_print(tty0, "!\n", gen_color(0xee, 0xee, 0xee), gen_color(0, 0, 0));
 
     // 初始化内核日志模块
 

src/kernel/memm/allocator/raw.c

@@ -7,54 +7,84 @@
 void raw_allocator_new(raw_allocator_t *allocator, usize size)
 {
     allocator->size = size - sizeof(allocator->size);
-    allocator->cells[0].capacity = size - sizeof(raw_allocator_t);
+    allocator->free_count = 0;
+    allocator->rest_memory = size - sizeof(raw_allocator_t);
+    allocator->cells[0].capacity = size - sizeof(raw_allocator_t) - sizeof(raw_allocator_cell);
     allocator->cells[0].length = 0;
 }
 
 void *raw_allocator_allocate(raw_allocator_t *allocator, usize size, usize align)
 {
-    usize rsize = size;
-    align_to(rsize, 16);
+    usize real_size = size;
+    align_to(real_size, 16);
     raw_allocator_cell *cell = allocator->cells;
-    while ((void *)cell + cell->capacity + sizeof(raw_allocator_cell) < (void *)allocator + allocator->size)
+    while ((void *)raw_allocator_next_cell(cell) < (void *)allocator + allocator->size)
     {
-        while (
-            (void *)cell + cell->capacity + sizeof(raw_allocator_cell) < (void *)allocator + allocator->size &&
+        while ( // 确保cell指向的内容还在这个allocator内
+            (void *)raw_allocator_next_cell(cell) < raw_allocator_end(allocator) &&
             cell->length != 0)
         {
-            cell = (void *)cell + cell->capacity + sizeof(raw_allocator_cell);
+            cell = raw_allocator_next_cell(cell);
         }
-        if (rsize <= cell->capacity)
+        if (real_size <= cell->capacity)
             break;
     }
-    if ((void *)cell < (void *)allocator + allocator->size)
+    if ((void *)cell < raw_allocator_end(allocator))
         goto fitable_cell_finded;
     else
         return nullptr;
 
 fitable_cell_finded:
     cell->length = size;
-    if (rsize < cell->capacity)
+    if (real_size < cell->capacity)
     {
         usize cap = cell->capacity;
-        cell->capacity = rsize;
-        raw_allocator_cell *ncell = (void *)cell + cell->capacity + sizeof(raw_allocator_cell);
-        ncell->capacity = cap - rsize - sizeof(raw_allocator_cell);
+        cell->capacity = real_size;
+        raw_allocator_cell *ncell = raw_allocator_next_cell(cell);
+        ncell->capacity = cap - real_size - sizeof(raw_allocator_cell);
         ncell->length = 0;
     }
+    allocator->rest_memory -= real_size;
     return cell->content;
 }
 
+static inline void raw_allocator_cellmerge(raw_allocator_t *allocator)
+{
+    raw_allocator_cell *cell = allocator->cells;
+    raw_allocator_cell *ncell = raw_allocator_next_cell(cell);
+    while ((void *)ncell < raw_allocator_end(allocator))
+    {
+        while ( // 首先保证ncell还在这个allocator内
+            (void *)ncell < raw_allocator_end(allocator) &&
+            cell->length == 0 && ncell->length == 0)
+        {
+            cell->capacity += ncell->capacity + sizeof(raw_allocator_cell);
+            ncell = raw_allocator_next_cell(ncell);
+        }
+        cell = ncell;
+        ncell = raw_allocator_next_cell(cell);
+    }
+}
+
 void raw_allocator_free(raw_allocator_t *allocator, void *mem)
 {
     raw_allocator_cell *cell = allocator->cells;
-    while ((void *)cell < (void *)allocator + allocator->size)
+    while ((void *)cell < raw_allocator_end(allocator))
     {
         if (mem == cell->content)
         {
             cell->length = 0;
             break;
         }
-        cell = (void *)cell + sizeof(raw_allocator_cell) + cell->capacity;
+        cell = raw_allocator_next_cell(cell);
+    }
+    allocator->rest_memory += cell->capacity + sizeof(raw_allocator_cell);
+    allocator->free_count++;
+    if ( // 可用内存不超过当前allocator的 5% 或调用free次数很多时
+        allocator->size / allocator->rest_memory > 20 &&
+        allocator->free_count > RAW_ALLOCATOR_FREE_MAX)
+    {
+        raw_allocator_cellmerge(allocator);
+        allocator->free_count = 0;
     }
 }