From 663e6c1df8721960c0a3bb6cd5dd047b610c3bad Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Thu, 5 Nov 2015 18:11:13 +0000 Subject: [PATCH] Don't sync dirty bitmaps in postcopy Once we're in postcopy the source processors are stopped and memory shouldn't change any more, so there's no need to look at the dirty map. There are two notes to this: 1) If we do resync and a page had changed then the page would get sent again, which the destination wouldn't allow (since it might have also modified the page) 2) Before disabling this I'd seen very rare cases where a page had been marked dirtied although the memory contents are apparently identical Signed-off-by: Dr. David Alan Gilbert Reviewed-by: David Gibson Reviewed-by: Juan Quintela Reviewed-by: Amit Shah Signed-off-by: Juan Quintela --- migration/ram.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/migration/ram.c b/migration/ram.c index 8bf0841fad..339b001daf 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1846,7 +1846,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque) { rcu_read_lock(); - migration_bitmap_sync(); + if (!migration_in_postcopy(migrate_get_current())) { + migration_bitmap_sync(); + } ram_control_before_iterate(f, RAM_CONTROL_FINISH); @@ -1881,7 +1883,8 @@ static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size, remaining_size = ram_save_remaining() * TARGET_PAGE_SIZE; - if (remaining_size < max_size) { + if (!migration_in_postcopy(migrate_get_current()) && + remaining_size < max_size) { qemu_mutex_lock_iothread(); rcu_read_lock(); migration_bitmap_sync(); -- 2.11.0