From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
Split out the finding of the dirty page and all the wrap detection
into a separate function since it was getting a bit hairy.
Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
---
migration/ram.c | 84 ++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 59 insertions(+), 25 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index 04e895c..8d0a388 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -917,6 +917,59 @@ static int ram_save_compressed_page(QEMUFile *f, RAMBlock
*block,
return pages;
}
+/*
+ * Find the next dirty page and update any state associated with
+ * the search process.
+ *
+ * Returns: True if a page is found
+ *
+ * @f: Current migration stream.
+ * @pss: Data about the state of the current dirty page scan.
+ * @*again: Set to false if the search has scanned the whole of RAM
+ */
+static bool find_dirty_block(QEMUFile *f, PageSearchStatus *pss,
+ bool *again)
+{
+ pss->offset = migration_bitmap_find_and_reset_dirty(pss->block,
+ pss->offset);
+ if (pss->complete_round && pss->block == last_seen_block &&
+ pss->offset >= last_offset) {
+ /*
+ * We've been once around the RAM and haven't found anything
+ * give up.
+ */
+ *again = false;
+ return false;
+ }
+ if (pss->offset >= pss->block->used_length) {
+ /* Didn't find anything in this RAM Block */
+ pss->offset = 0;
+ pss->block = QLIST_NEXT_RCU(pss->block, next);
+ if (!pss->block) {
+ /* Hit the end of the list */
+ pss->block = QLIST_FIRST_RCU(&ram_list.blocks);
+ /* Flag that we've looped */
+ pss->complete_round = true;
+ ram_bulk_stage = false;
+ if (migrate_use_xbzrle()) {
+ /* If xbzrle is on, stop using the data compression at this
+ * point. In theory, xbzrle can do better than compression.
+ */
+ flush_compressed_data(f);
+ compression_switch = false;
+ }
+ }
+ /* Didn't find anything this time, but try again on the new block */
+ *again = true;
+ return false;
+ } else {
+ /* Can go around again, but... */
+ *again = true;
+ /* We've found something so probably don't need to */
+ return true;
+ }
+}
+
/**
* ram_find_and_save_block: Finds a dirty page and sends it to f
*
@@ -935,6 +988,7 @@ static int ram_find_and_save_block(QEMUFile *f, bool
last_stage,
{
PageSearchStatus pss;
int pages = 0;
+ bool again, found;
pss.block = last_seen_block;
pss.offset = last_offset;
@@ -944,29 +998,10 @@ static int ram_find_and_save_block(QEMUFile *f, bool
last_stage,
pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
}
- while (true) {
- pss.offset = migration_bitmap_find_and_reset_dirty(pss.block,
- pss.offset);
- if (pss.complete_round && pss.block == last_seen_block &&
- pss.offset >= last_offset) {
- break;
- }
- if (pss.offset >= pss.block->used_length) {
- pss.offset = 0;
- pss.block = QLIST_NEXT_RCU(pss.block, next);
- if (!pss.block) {
- pss.block = QLIST_FIRST_RCU(&ram_list.blocks);
- pss.complete_round = true;
- ram_bulk_stage = false;
- if (migrate_use_xbzrle()) {
- /* If xbzrle is on, stop using the data compression at this
- * point. In theory, xbzrle can do better than compression.
- */
- flush_compressed_data(f);
- compression_switch = false;
- }
- }
- } else {
+ do {
+ found = find_dirty_block(f, &pss, &again);
+
+ if (found) {
if (compression_switch && migrate_use_compression()) {
pages = ram_save_compressed_page(f, pss.block, pss.offset,
last_stage,
@@ -979,10 +1014,9 @@ static int ram_find_and_save_block(QEMUFile *f, bool
last_stage,
/* if page is unmodified, continue to the next */
if (pages > 0) {
last_sent_block = pss.block;
- break;
}
}
- }
+ } while (!pages && again);
last_seen_block = pss.block;
last_offset = pss.offset;
--
2.5.0
