[libvirt] [RFC] Add uptime to API returning Dom Info

[Nehal J Wani]

This is an attempt to fix: https://bugzilla.redhat.com/show_bug.cgi?id=812911

Calculate vm uptime by subtracting process starttime from system uptime:
Almost equivalent to:
echo $(($(($(awk '{print $1}' /proc/uptime)*1e9 - $(($(cut -d " " -f22 /proc/$PID/stat)*1e7))))/(1.0 * 1e9)))

---
 include/libvirt/libvirt-domain.h |  1 +
 src/qemu/qemu_driver.c           | 32 +++++++++++++++++++++++++-------
 src/remote/remote_protocol.x     |  1 +
 src/remote_protocol-structs      |  1 +
 tools/virsh-domain-monitor.c     |  8 ++++++++
 5 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/include/libvirt/libvirt-domain.h b/include/libvirt/libvirt-domain.h
index 7be4219..2df0241 100644
--- a/include/libvirt/libvirt-domain.h
+++ b/include/libvirt/libvirt-domain.h
@@ -275,6 +275,7 @@ struct _virDomainInfo {
     unsigned long memory;       /* the memory in KBytes used by the domain */
     unsigned short nrVirtCpu;   /* the number of virtual CPUs for the domain */
     unsigned long long cpuTime; /* the CPU time used in nanoseconds */
+    unsigned long long upTime;  /* the total uptime in nanoseconds */
 };
 
 /**
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index f07e4fb..0b5098f 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1309,11 +1309,12 @@ static char *qemuConnectGetCapabilities(virConnectPtr conn) {
 
 static int
 qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long *vm_rss,
-                   pid_t pid, int tid)
+                   pid_t pid, int tid, unsigned long long *upTime)
 {
     char *proc;
     FILE *pidinfo;
-    unsigned long long usertime = 0, systime = 0;
+    unsigned long long usertime = 0, systime = 0, starttime = 0;
+    double _uptime;
     long rss = 0;
     int cpu = 0;
     int ret;
@@ -1337,13 +1338,29 @@ qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long *vm_rss,
                /* pid -> stime */
                "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %llu %llu"
                /* cutime -> endcode */
-               "%*d %*d %*d %*d %*d %*d %*u %*u %ld %*u %*u %*u"
+               "%*d %*d %*d %*d %*d %*d %llu %*u %ld %*u %*u %*u"
                /* startstack -> processor */
                "%*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*d %d",
-               &usertime, &systime, &rss, &cpu) != 4) {
+               &usertime, &systime, &starttime, &rss, &cpu) != 5) {
         VIR_WARN("cannot parse process status data");
     }
 
+    ret = virAsprintf(&proc, "/proc/uptime");
+    if (ret < 0)
+        return -1;
+
+    pidinfo = fopen(proc, "r");
+    VIR_FREE(proc);
+
+    if (!pidinfo || fscanf(pidinfo, "%lf %*f", &_uptime) != 1) {
+        VIR_WARN("cannot parse machine uptime data");
+    }
+
+    if (upTime)
+        *upTime = 1000ull * 1000ull * 1000ull * _uptime -
+            (1000ull * 1000ull * 1000ull * starttime)
+            / (unsigned long long)sysconf(_SC_CLK_TCK);
+
     /* We got jiffies
      * We want nanoseconds
      * _SC_CLK_TCK is jiffies per second
@@ -1404,7 +1421,8 @@ qemuDomainHelperGetVcpus(virDomainObjPtr vm, virVcpuInfoPtr info, int maxinfo,
                                        &(info[i].cpu),
                                        NULL,
                                        vm->pid,
-                                       priv->vcpupids[i]) < 0) {
+                                       priv->vcpupids[i],
+                                       NULL) < 0) {
                     virReportSystemError(errno, "%s",
                                          _("cannot get vCPU placement & pCPU time"));
                     return -1;
@@ -2595,7 +2613,7 @@ static int qemuDomainGetInfo(virDomainPtr dom,
     if (!virDomainObjIsActive(vm)) {
         info->cpuTime = 0;
     } else {
-        if (qemuGetProcessInfo(&(info->cpuTime), NULL, NULL, vm->pid, 0) < 0) {
+        if (qemuGetProcessInfo(&(info->cpuTime), NULL, NULL, vm->pid, 0, &(info->upTime)) < 0) {
             virReportError(VIR_ERR_OPERATION_FAILED, "%s",
                            _("cannot read cputime for domain"));
             goto cleanup;
@@ -11474,7 +11492,7 @@ qemuDomainMemoryStats(virDomainPtr dom,
 
         if (ret >= 0 && ret < nr_stats) {
             long rss;
-            if (qemuGetProcessInfo(NULL, NULL, &rss, vm->pid, 0) < 0) {
+            if (qemuGetProcessInfo(NULL, NULL, &rss, vm->pid, 0, NULL) < 0) {
                 virReportError(VIR_ERR_OPERATION_FAILED, "%s",
                                _("cannot get RSS for domain"));
             } else {
diff --git a/src/remote/remote_protocol.x b/src/remote/remote_protocol.x
index d90e6b5..193f501 100644
--- a/src/remote/remote_protocol.x
+++ b/src/remote/remote_protocol.x
@@ -901,6 +901,7 @@ struct remote_domain_get_info_ret { /* insert at 1 */
     unsigned hyper memory;
     unsigned short nrVirtCpu;
     unsigned hyper cpuTime;
+    unsigned hyper upTime;
 };
 
 struct remote_domain_save_args {
diff --git a/src/remote_protocol-structs b/src/remote_protocol-structs
index e614f77..1f54d5d 100644
--- a/src/remote_protocol-structs
+++ b/src/remote_protocol-structs
@@ -531,6 +531,7 @@ struct remote_domain_get_info_ret {
         uint64_t                   memory;
         u_short                    nrVirtCpu;
         uint64_t                   cpuTime;
+        uint64_t                   upTime;
 };
 struct remote_domain_save_args {
         remote_nonnull_domain      dom;
diff --git a/tools/virsh-domain-monitor.c b/tools/virsh-domain-monitor.c
index 6951db2..027790f 100644
--- a/tools/virsh-domain-monitor.c
+++ b/tools/virsh-domain-monitor.c
@@ -1246,6 +1246,14 @@ cmdDominfo(vshControl *ctl, const vshCmd *cmd)
             vshPrint(ctl, "%-15s %.1lfs\n", _("CPU time:"), cpuUsed);
         }
 
+        if (info.upTime != 0) {
+            double upTime = info.upTime;
+
+            upTime /= 1000000000.0;
+
+            vshPrint(ctl, "%-15s %.1lfs\n", _("Uptime:"), upTime);
+        }
+
         if (info.maxMem != UINT_MAX)
             vshPrint(ctl, "%-15s %lu KiB\n", _("Max memory:"),
                  info.maxMem);
-- 
2.1.0