[PATCH v4 22/23] migration: Use multifd before we check for the zero page

[Juan Quintela]

So we use multifd to transmit zero pages.

Signed-off-by: Juan Quintela <quint...@redhat.com>
---
 migration/ram.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/migration/ram.c b/migration/ram.c
index 3536778e19..bdc7cec4cd 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -2168,6 +2168,32 @@ static int ram_save_target_page_legacy(RAMState *rs, 
PageSearchStatus *pss)
     return ram_save_page(rs, pss);
 }
 
+/**
+ * ram_save_target_page_multifd: save one target page
+ *
+ * Returns the number of pages written
+ *
+ * @rs: current RAM state
+ * @pss: data about the page we want to send
+ */
+static int ram_save_target_page_multifd(RAMState *rs, PageSearchStatus *pss)
+{
+    RAMBlock *block = pss->block;
+    ram_addr_t offset = ((ram_addr_t)pss->page) << TARGET_PAGE_BITS;
+    int res;
+
+    if (!migration_in_postcopy()) {
+        return ram_save_multifd_page(rs, block, offset);
+    }
+
+    res = save_zero_page(rs, block, offset);
+    if (res > 0) {
+        return res;
+    }
+
+    return ram_save_page(rs, pss);
+}
+
 /**
  * ram_save_host_page: save a whole host page
  *
@@ -3011,7 +3037,11 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     ram_control_before_iterate(f, RAM_CONTROL_SETUP);
     ram_control_after_iterate(f, RAM_CONTROL_SETUP);
 
-    (*rsp)->ram_save_target_page = ram_save_target_page_legacy;
+    if (migrate_use_multifd()) {
+        (*rsp)->ram_save_target_page = ram_save_target_page_multifd;
+    } else {
+        (*rsp)->ram_save_target_page = ram_save_target_page_legacy;
+    }
     multifd_send_sync_main(f);
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
     qemu_fflush(f);
-- 
2.34.1