migration: print expected downtime in info migrate

Signed-off-by: Juan Quintela <quintela@redhat.com>

arch_init.c

@@ -539,6 +539,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
     int ret;
     int i;
     uint64_t expected_downtime;
+    MigrationState *s = migrate_get_current();
 
     bytes_transferred_last = bytes_transferred;
     bwidth = qemu_get_clock_ns(rt_clock);
@@ -593,6 +594,7 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
     if (expected_downtime <= migrate_max_downtime()) {
         memory_global_sync_dirty_bitmap(get_system_memory());
         expected_downtime = ram_save_remaining() * TARGET_PAGE_SIZE / bwidth;
+        s->expected_downtime = expected_downtime / 1000000; /* ns -> ms */
 
         return expected_downtime <= migrate_max_downtime();
     }

hmp.c

@@ -152,6 +152,10 @@ void hmp_info_migrate(Monitor *mon)
         monitor_printf(mon, "Migration status: %s\n", info->status);
         monitor_printf(mon, "total time: %" PRIu64 " milliseconds\n",
                        info->total_time);
+        if (info->has_expected_downtime) {
+            monitor_printf(mon, "expected downtime: %" PRIu64 " milliseconds\n",
+                           info->expected_downtime);
+        }
         if (info->has_downtime) {
             monitor_printf(mon, "downtime: %" PRIu64 " milliseconds\n",
                            info->downtime);

migration.c

@@ -169,6 +169,8 @@ MigrationInfo *qmp_query_migrate(Error **errp)
         info->has_total_time = true;
         info->total_time = qemu_get_clock_ms(rt_clock)
             - s->total_time;
+        info->has_expected_downtime = true;
+        info->expected_downtime = s->expected_downtime;
 
         info->has_ram = true;
         info->ram = g_malloc0(sizeof(*info->ram));

migration.h

@@ -41,6 +41,7 @@ struct MigrationState
     MigrationParams params;
     int64_t total_time;
     int64_t downtime;
+    int64_t expected_downtime;
     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
     int64_t xbzrle_cache_size;
 };

qapi-schema.json

@@ -442,6 +442,10 @@
 #        total downtime in milliseconds for the guest.
 #        (since 1.3)
 #
+# @expected-downtime: #optional only present while migration is active
+#        expected downtime in milliseconds for the guest in last walk
+#        of the dirty bitmap. (since 1.3)
+#
 # Since: 0.14.0
 ##
 { 'type': 'MigrationInfo',
@@ -449,6 +453,7 @@
            '*disk': 'MigrationStats',
            '*xbzrle-cache': 'XBZRLECacheStats',
            '*total-time': 'int',
+           '*expected-downtime': 'int',
            '*downtime': 'int'} }
 
 ##

qmp-commands.hx

@@ -2306,6 +2306,9 @@ The main json-object contains the following:
 		 time (json-int)
 - "downtime": only present when migration has finished correctly
               total amount in ms for downtime that happened (json-int)
+- "expected-downtime": only present while migration is active
+                total amount in ms for downtime that was calculated on
+		the last bitmap round (json-int)
 - "ram": only present if "status" is "active", it is a json-object with the
   following RAM information (in bytes):
          - "transferred": amount transferred (json-int)
@@ -2367,6 +2370,7 @@ Examples:
             "remaining":123,
             "total":246,
             "total-time":12345,
+            "expected-downtime":12345,
             "duplicate":123,
             "normal":123,
             "normal-bytes":123456
@@ -2385,6 +2389,7 @@ Examples:
             "remaining":1053304,
             "transferred":3720,
             "total-time":12345,
+            "expected-downtime":12345,
             "duplicate":123,
             "normal":123,
             "normal-bytes":123456
@@ -2409,6 +2414,7 @@ Examples:
             "remaining":1053304,
             "transferred":3720,
             "total-time":12345,
+            "expected-downtime":12345,
             "duplicate":10,
             "normal":3333,
             "normal-bytes":3412992