During migration, we would sync bitmap from ram_list.dirty_memory to
RAMBlock.bmap in cpu_physical_memory_sync_dirty_bitmap().
Since we set RAMBlock.bmap and ram_list.dirty_memory both to all 1, this
means at the first round this sync is meaningless and is a duplicated
work.
Leaving RAMBlock->bmap blank on allocating would have a side effect on
migration_dirty_pages, since it is calculated from the result of
cpu_physical_memory_sync_dirty_bitmap(). To keep it right, we need to
set migration_dirty_pages to 0 in ram_state_init().
Signed-off-by: Wei Yang <richardw.y...@linux.intel.com>
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
---
v2: add a comment explaining why leaving RAMBlock.bmap clear
---
migration/ram.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 4c60869226..e9a27ea5e6 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3181,12 +3181,7 @@ static int ram_state_init(RAMState **rsp)
qemu_mutex_init(&(*rsp)->src_page_req_mutex);
QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
- /*
- * Count the total number of pages used by ram blocks not including any
- * gaps due to alignment or unplugs.
- */
- (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
-
+ (*rsp)->migration_dirty_pages = 0;
ram_state_reset(*rsp);
return 0;
@@ -3201,8 +3196,15 @@ static void ram_list_init_bitmaps(void)
if (ram_bytes_total()) {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
pages = block->max_length >> TARGET_PAGE_BITS;
+ /*
+ * We leave RAMBlock.bmap clear here and they will be sync from
+ * ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] in
+ * migration_bitmap_sync_precopy().
+ *
+ * ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] is set to all 1
+ * in ram_block_add().
+ */
block->bmap = bitmap_new(pages);
- bitmap_set(block->bmap, 0, pages);
if (migrate_postcopy_ram()) {
block->unsentmap = bitmap_new(pages);
bitmap_set(block->unsentmap, 0, pages);
--
2.19.1
