exec: sort the memory from biggest to smallest

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

arch_init.c

@@ -505,35 +505,6 @@ uint64_t ram_bytes_total(void)
     return total;
 }
 
-static int block_compar(const void *a, const void *b)
-{
-    RAMBlock * const *ablock = a;
-    RAMBlock * const *bblock = b;
-
-    return strcmp((*ablock)->idstr, (*bblock)->idstr);
-}
-
-static void sort_ram_list(void)
-{
-    RAMBlock *block, *nblock, **blocks;
-    int n;
-    n = 0;
-    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
-        ++n;
-    }
-    blocks = g_malloc(n * sizeof *blocks);
-    n = 0;
-    QTAILQ_FOREACH_SAFE(block, &ram_list.blocks, next, nblock) {
-        blocks[n++] = block;
-        QTAILQ_REMOVE(&ram_list.blocks, block, next);
-    }
-    qsort(blocks, n, sizeof *blocks, block_compar);
-    while (--n >= 0) {
-        QTAILQ_INSERT_HEAD(&ram_list.blocks, blocks[n], next);
-    }
-    g_free(blocks);
-}
-
 static void migration_end(void)
 {
     if (migration_bitmap) {
@@ -562,7 +533,6 @@ static void reset_ram_globals(void)
 {
     last_block = NULL;
     last_offset = 0;
-    sort_ram_list();
 }
 
 #define MAX_WAIT 50 /* ms, half buffered_file limit */

exec.c

@@ -1007,7 +1007,7 @@ static int memory_try_enable_merging(void *addr, size_t len)
 ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
                                    MemoryRegion *mr)
 {
-    RAMBlock *new_block;
+    RAMBlock *block, *new_block;
 
     size = TARGET_PAGE_ALIGN(size);
     new_block = g_malloc0(sizeof(*new_block));
@@ -1043,7 +1043,17 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
     }
     new_block->length = size;
 
-    QTAILQ_INSERT_HEAD(&ram_list.blocks, new_block, next);
+    /* Keep the list sorted from biggest to smallest block.  */
+    QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+        if (block->length < new_block->length) {
+            break;
+        }
+    }
+    if (block) {
+        QTAILQ_INSERT_BEFORE(block, new_block, next);
+    } else {
+        QTAILQ_INSERT_TAIL(&ram_list.blocks, new_block, next);
+    }
     ram_list.mru_block = NULL;
 
     ram_list.phys_dirty = g_realloc(ram_list.phys_dirty,