[Qemu-devel] [PATCH COLO-Frame v14 30/40] COLO: Split qemu_savevm_state_begin out of checkpoint process

[zhanghailiang <zhang.zhanghailiang@huawei.com>]

It is unnecessary to call qemu_savevm_state_begin() in every checkponit process.
It mainly sets up devices and does the first device state pass. These data will
not change during the later checkpoint process. So, we split it out of
colo_do_checkpoint_transaction(), in this way, we can reduce these data
transferring in the later checkpoint.

Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
v13:
- Fix some minor issues found by Dave
- Add Reviewed-by tag
---
 migration/colo.c | 51 ++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/migration/colo.c b/migration/colo.c
index 9ac46ec..98a12fc 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -293,16 +293,6 @@ static int colo_do_checkpoint_transaction(MigrationState *s,
         goto out;
     }
 
-    /* Disable block migration */
-    s->params.blk = 0;
-    s->params.shared = 0;
-    qemu_savevm_state_begin(s->to_dst_file, &s->params);
-    ret = qemu_file_get_error(s->to_dst_file);
-    if (ret < 0) {
-        error_report("Save vm state begin error");
-        goto out;
-    }
-
     qemu_mutex_lock_iothread();
     /*
     * Only save VM's live state, which not including device state.
@@ -375,6 +365,21 @@ out:
     return ret;
 }
 
+static int colo_prepare_before_save(MigrationState *s)
+{
+    int ret;
+
+    /* Disable block migration */
+    s->params.blk = 0;
+    s->params.shared = 0;
+    qemu_savevm_state_begin(s->to_dst_file, &s->params);
+    ret = qemu_file_get_error(s->to_dst_file);
+    if (ret < 0) {
+        error_report("Save vm state begin error");
+    }
+    return ret;
+}
+
 static void colo_process_checkpoint(MigrationState *s)
 {
     QEMUSizedBuffer *buffer = NULL;
@@ -390,6 +395,11 @@ static void colo_process_checkpoint(MigrationState *s)
         goto out;
     }
 
+    ret = colo_prepare_before_save(s);
+    if (ret < 0) {
+        goto out;
+    }
+
     /*
      * Wait for Secondary finish loading vm states and enter COLO
      * restore.
@@ -515,6 +525,17 @@ static void colo_wait_handle_cmd(QEMUFile *f, int *checkpoint_request,
     }
 }
 
+static int colo_prepare_before_load(QEMUFile *f)
+{
+    int ret;
+
+    ret = qemu_loadvm_state_begin(f);
+    if (ret < 0) {
+        error_report("load vm state begin error, ret=%d", ret);
+    }
+    return ret;
+}
+
 void *colo_process_incoming_thread(void *opaque)
 {
     MigrationIncomingState *mis = opaque;
@@ -555,6 +576,11 @@ void *colo_process_incoming_thread(void *opaque)
         goto out;
     }
 
+    ret = colo_prepare_before_load(mis->from_src_file);
+    if (ret < 0) {
+        goto out;
+    }
+
     colo_put_cmd(mis->to_src_file, COLO_MESSAGE_CHECKPOINT_READY,
                  &local_err);
     if (local_err) {
@@ -587,11 +613,6 @@ void *colo_process_incoming_thread(void *opaque)
             goto out;
         }
 
-        ret = qemu_loadvm_state_begin(mis->from_src_file);
-        if (ret < 0) {
-            error_report("Load vm state begin error, ret=%d", ret);
-            goto out;
-        }
         ret = qemu_loadvm_state_main(mis->from_src_file, mis);
         if (ret < 0) {
             error_report("Load VM's live state (ram) error");
-- 
1.8.3.1