[Qemu-devel] [PULL 46/57] Don't sync dirty bitmaps in postcopy
From: "Dr. David Alan Gilbert" 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 8bf0841..339b001 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(); -- 2.5.0
[Qemu-devel] [PULL 46/57] Don't sync dirty bitmaps in postcopy
From: "Dr. David Alan Gilbert" 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 8bf0841..339b001 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(); -- 2.5.0