[PATCH v2] migration: Count new_dirty instead of real_dirty

[Keqian Zhu]

real_dirty_pages becomes equal to total ram size after dirty log sync
in ram_init_bitmaps, the reason is that the bitmap of ramblock is
initialized to be all set, so old path counts them as "real dirty" at
beginning.

This causes wrong dirty rate and false positive throttling at the end
of first ram save iteration.

Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>

---
Changelog:

v2:
 - use new_dirty_pages instead of accu_dirty_pages.
 - adjust commit messages.

---
 include/exec/ram_addr.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 7b5c24e928..a95e2e7c25 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -443,7 +443,7 @@ static inline
 uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                                                ram_addr_t start,
                                                ram_addr_t length,
-                                               uint64_t *real_dirty_pages)
+                                               uint64_t *new_dirty_pages)
 {
     ram_addr_t addr;
     unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
@@ -469,7 +469,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
             if (src[idx][offset]) {
                 unsigned long bits = atomic_xchg(&src[idx][offset], 0);
                 unsigned long new_dirty;
-                *real_dirty_pages += ctpopl(bits);
                 new_dirty = ~dest[k];
                 dest[k] |= bits;
                 new_dirty &= bits;
@@ -502,7 +501,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
                         start + addr + offset,
                         TARGET_PAGE_SIZE,
                         DIRTY_MEMORY_MIGRATION)) {
-                *real_dirty_pages += 1;
                 long k = (start + addr) >> TARGET_PAGE_BITS;
                 if (!test_and_set_bit(k, dest)) {
                     num_dirty++;
@@ -511,6 +509,7 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
         }
     }
 
+    *new_dirty_pages += num_dirty;
     return num_dirty;
 }
 #endif
-- 
2.19.1