qemu: expand domain memory statistics with 'usable'

'memtotal' in virtio drivers and qemu corresponds to 'available' in libvirt.
Because of that, 'stat-available-memory' is renamed into 'usable'.
Balloon statistics are not reported in hrf, so no modifications are made in qemu_monitor_text.c.
Signed-off-by: NDerbyshev Dmitry <dderbyshev@virtuozzo.com>

include/libvirt/libvirt-domain.h

@@ -603,11 +603,17 @@ typedef enum {
      * is in kB */
     VIR_DOMAIN_MEMORY_STAT_RSS             = 7,
 
+    /*
+     * How big the balloon can be inflated without pushing the guest system
+     * to swap, corresponds to 'Available' in /proc/meminfo
+     */
+    VIR_DOMAIN_MEMORY_STAT_USABLE          = 8,
+
     /*
      * The number of statistics supported by this version of the interface.
      * To add new statistics, add them to the enum and increase this value.
      */
-    VIR_DOMAIN_MEMORY_STAT_NR              = 8,
+    VIR_DOMAIN_MEMORY_STAT_NR              = 9,
 
 # ifdef VIR_ENUM_SENTINELS
     VIR_DOMAIN_MEMORY_STAT_LAST = VIR_DOMAIN_MEMORY_STAT_NR

src/libvirt-domain.c

@@ -5986,6 +5986,9 @@ virDomainGetInterfaceParameters(virDomainPtr domain,
  *     The amount of memory which is not being used for any purpose (in kb).
  * VIR_DOMAIN_MEMORY_STAT_AVAILABLE:
  *     The total amount of memory available to the domain's OS (in kb).
+ * VIR_DOMAIN_MEMORY_STAT_USABLE:
+ *     How big the balloon can be inflated without pushing the guest system
+ *     to swap, corresponds to 'Available' in /proc/meminfo
  * VIR_DOMAIN_MEMORY_STAT_ACTUAL_BALLOON:
  *     Current balloon value (in kb).
  *

src/qemu/qemu_monitor_json.c

@@ -1719,6 +1719,8 @@ int qemuMonitorJSONGetMemoryStats(qemuMonitorPtr mon,
                       VIR_DOMAIN_MEMORY_STAT_UNUSED, 1024);
     GET_BALLOON_STATS("stat-total-memory",
                       VIR_DOMAIN_MEMORY_STAT_AVAILABLE, 1024);
+    GET_BALLOON_STATS("stat-available-memory",
+                      VIR_DOMAIN_MEMORY_STAT_USABLE, 1024);
     ret = got;
  cleanup:
     virJSONValueFree(cmd);

tools/virsh-domain-monitor.c

@@ -369,6 +369,8 @@ cmdDomMemStat(vshControl *ctl, const vshCmd *cmd)
             vshPrint(ctl, "unused %llu\n", stats[i].val);
         if (stats[i].tag == VIR_DOMAIN_MEMORY_STAT_AVAILABLE)
             vshPrint(ctl, "available %llu\n", stats[i].val);
+        if (stats[i].tag == VIR_DOMAIN_MEMORY_STAT_USABLE)
+            vshPrint(ctl, "usable %llu\n", stats[i].val);
         if (stats[i].tag == VIR_DOMAIN_MEMORY_STAT_ACTUAL_BALLOON)
             vshPrint(ctl, "actual %llu\n", stats[i].val);
         if (stats[i].tag == VIR_DOMAIN_MEMORY_STAT_RSS)