monitor/hmp-cmds: improvements for the 'info migrate'

When running:

(qemu) info migrate
globals:
store-global-state: on
only-migratable: off
...
xbzrle transferred: 640892 kbytes
xbzrle pages: 16645936 pages
xbzrle cache miss: 1525426
xbzrle cache miss rate: 0.09
xbzrle encoding rate: 91.42
xbzrle overflow: 40896
...
compression pages: 377710 pages
compression busy: 0
compression busy rate: 0.00
compressed size: 463169457
compression rate: 3.33

Add units for 'xbzrle cache miss' and 'compressed size',
make it easier to read.

Suggested-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Mao Zhongyi <maozhongyi@cmss.chinamobile.com>
Message-Id: <20200603080904.997083-8-maozhongyi@cmss.chinamobile.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

docs/xbzrle.txt

@@ -112,7 +112,7 @@ is recommended.
     cache size: H bytes
     xbzrle transferred: I kbytes
     xbzrle pages: J pages
-    xbzrle cache miss: K
+    xbzrle cache miss: K pages
     xbzrle overflow: L
 
 xbzrle cache-miss: the number of cache misses to date - high cache-miss rate

monitor/hmp-cmds.c

@@ -299,7 +299,7 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->xbzrle_cache->bytes >> 10);
         monitor_printf(mon, "xbzrle pages: %" PRIu64 " pages\n",
                        info->xbzrle_cache->pages);
-        monitor_printf(mon, "xbzrle cache miss: %" PRIu64 "\n",
+        monitor_printf(mon, "xbzrle cache miss: %" PRIu64 " pages\n",
                        info->xbzrle_cache->cache_miss);
         monitor_printf(mon, "xbzrle cache miss rate: %0.2f\n",
                        info->xbzrle_cache->cache_miss_rate);
@@ -316,8 +316,8 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->compression->busy);
         monitor_printf(mon, "compression busy rate: %0.2f\n",
                        info->compression->busy_rate);
-        monitor_printf(mon, "compressed size: %" PRIu64 "\n",
-                       info->compression->compressed_size);
+        monitor_printf(mon, "compressed size: %" PRIu64 " kbytes\n",
+                       info->compression->compressed_size >> 10);
         monitor_printf(mon, "compression rate: %0.2f\n",
                        info->compression->compression_rate);
     }