memory: use find_next_bit() to find dirty bits

This operation is way faster than doing it bit by bit.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Orit Wasserman <owasserm@redhat.com>

1 files changed, 6 insertions, 10 deletions

diff --git a/include/exec/memory-internal.h b/include/exec/memory-internal.h
index c04a92a2d9..b017c2ec98 100644
--- a/include/exec/memory-internal.h
+++ b/include/exec/memory-internal.h
@@ -44,19 +44,15 @@ static inline bool cpu_physical_memory_get_dirty(ram_addr_t start,
                                                  ram_addr_t length,
                                                  unsigned client)
 {
-    ram_addr_t addr, end;
+    unsigned long end, page, next;
 
     assert(client < DIRTY_MEMORY_NUM);
 
-    end = TARGET_PAGE_ALIGN(start + length);
-    start &= TARGET_PAGE_MASK;
-    for (addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
-        if (test_bit(addr >> TARGET_PAGE_BITS,
-                     ram_list.dirty_memory[client])) {
-            return true;
-        }
-    }
-    return false;
+    end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
+    page = start >> TARGET_PAGE_BITS;
+    next = find_next_bit(ram_list.dirty_memory[client], end, page);
+
+    return next < end;
 }
 
 static inline bool cpu_physical_memory_get_dirty_flag(ram_addr_t addr,