From 03158519384f15890d587937bd1b3ea699898e55 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Tue, 4 Jun 2019 14:17:27 +0800 Subject: [PATCH] migratioin/ram: leave RAMBlock->bmap blank on allocating 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 Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/ram.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 03a9cce9f9..082aea9d23 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -3173,11 +3173,11 @@ static int ram_state_init(RAMState **rsp) 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. + * This must match with the initial values of dirty bitmap. + * Currently we initialize the dirty bitmap to all zeros so + * here the total dirty page count is zero. */ - (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS; - + (*rsp)->migration_dirty_pages = 0; ram_state_reset(*rsp); return 0; @@ -3192,8 +3192,16 @@ static void ram_list_init_bitmaps(void) if (ram_bytes_total()) { RAMBLOCK_FOREACH_NOT_IGNORED(block) { pages = block->max_length >> TARGET_PAGE_BITS; + /* + * The initial dirty bitmap for migration must be set with all + * ones to make sure we'll migrate every guest RAM page to + * destination. + * Here we didn't set RAMBlock.bmap simply because it is already + * set in ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] in + * ram_block_add, and that's where we'll sync the dirty bitmaps. + * Here setting RAMBlock.bmap would be fine too but not necessary. + */ 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);