migration: Use migration_transferred_bytes() to calculate rate_limit

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20230515195709.63843-9-quintela@redhat.com>

migration/migration-stats.c

@@ -24,7 +24,9 @@ bool migration_rate_exceeded(QEMUFile *f)
         return true;
     }
 
-    uint64_t rate_limit_used = stat64_get(&mig_stats.rate_limit_used);
+    uint64_t rate_limit_start = stat64_get(&mig_stats.rate_limit_start);
+    uint64_t rate_limit_current = migration_transferred_bytes(f);
+    uint64_t rate_limit_used = rate_limit_current - rate_limit_start;
     uint64_t rate_limit_max = stat64_get(&mig_stats.rate_limit_max);
 
     if (rate_limit_max == RATE_LIMIT_DISABLED) {
@@ -51,9 +53,10 @@ void migration_rate_set(uint64_t limit)
     stat64_set(&mig_stats.rate_limit_max, limit / XFER_LIMIT_RATIO);
 }
 
-void migration_rate_reset(void)
+void migration_rate_reset(QEMUFile *f)
 {
     stat64_set(&mig_stats.rate_limit_used, 0);
+    stat64_set(&mig_stats.rate_limit_start, migration_transferred_bytes(f));
 }
 
 void migration_rate_account(uint64_t len)

migration/migration-stats.h

@@ -81,6 +81,10 @@ typedef struct {
      * Number of bytes sent during precopy stage.
      */
     Stat64 precopy_bytes;
+    /*
+     * Amount of transferred data at the start of current cycle.
+     */
+    Stat64 rate_limit_start;
     /*
      * Maximum amount of data we can send in a cycle.
      */
@@ -122,8 +126,10 @@ uint64_t migration_rate_get(void);
  * migration_rate_reset: Reset the rate limit counter.
  *
  * This is called when we know we start a new transfer cycle.
+ *
+ * @f: QEMUFile used for main migration channel
  */
-void migration_rate_reset(void);
+void migration_rate_reset(QEMUFile *f);
 
 /**
  * migration_rate_set: Set the maximum amount that can be transferred.

migration/migration.c

@@ -2692,7 +2692,7 @@ static void migration_update_counters(MigrationState *s,
             stat64_get(&mig_stats.dirty_bytes_last_sync) / bandwidth;
     }
 
-    migration_rate_reset();
+    migration_rate_reset(s->to_dst_file);
 
     update_iteration_initial_status(s);