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authorDr. David Alan Gilbert <dgilbert@redhat.com>2014-03-27 15:01:48 +0000
committerJuan Quintela <quintela@redhat.com>2014-05-05 22:15:03 +0200
commite30d1d8c7195848abb28a8c734a82b845b8b456a (patch)
tree004856d6bbeb5e699d3572c676cd3adbe6d6b867
parent548f52ea06951c20f0b91cae6cde0512ec073c83 (diff)
Count used RAMBlock pages for migration_dirty_pages
This is a fix for a bug* triggered by a migration after hot unplugging a few virtio-net NICs, that caused migration never to converge, because 'migration_dirty_pages' is incorrectly initialised. 'migration_dirty_pages' is used as a tally of the number of outstanding dirty pages, to give the migration code an idea of how much more data will need to be transferred, and thus whether it can end the iterative phase. It was initialised to the total size of the RAMBlock address space, however hotunplug can leave this space sparse, and hence migration_dirty_pages ended up too large. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> (* https://bugzilla.redhat.com/show_bug.cgi?id=1074913 ) Signed-off-by: Juan Quintela <quintela@redhat.com>
-rw-r--r--arch_init.c21
1 files changed, 17 insertions, 4 deletions
diff --git a/arch_init.c b/arch_init.c
index 60c975db2b..0c8c07d6ba 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -726,11 +726,8 @@ static void reset_ram_globals(void)
static int ram_save_setup(QEMUFile *f, void *opaque)
{
RAMBlock *block;
- int64_t ram_pages = last_ram_offset() >> TARGET_PAGE_BITS;
+ int64_t ram_bitmap_pages; /* Size of bitmap in pages, including gaps */
- migration_bitmap = bitmap_new(ram_pages);
- bitmap_set(migration_bitmap, 0, ram_pages);
- migration_dirty_pages = ram_pages;
mig_throttle_on = false;
dirty_rate_high_cnt = 0;
@@ -770,6 +767,22 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
bytes_transferred = 0;
reset_ram_globals();
+ ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS;
+ migration_bitmap = bitmap_new(ram_bitmap_pages);
+ bitmap_set(migration_bitmap, 0, ram_bitmap_pages);
+
+ /*
+ * Count the total number of pages used by ram blocks not including any
+ * gaps due to alignment or unplugs.
+ */
+ migration_dirty_pages = 0;
+ QTAILQ_FOREACH(block, &ram_list.blocks, next) {
+ uint64_t block_pages;
+
+ block_pages = block->length >> TARGET_PAGE_BITS;
+ migration_dirty_pages += block_pages;
+ }
+
memory_global_dirty_log_start();
migration_bitmap_sync();
qemu_mutex_unlock_iothread();