Added optional container checkpointing statistics

This adds the parameter '--print-stats' to 'podman container checkpoint'.
With '--print-stats' Podman will measure how long Podman itself, the OCI
runtime and CRIU requires to create a checkpoint and print out these
information. CRIU already creates checkpointing statistics which are
just read in addition to the added measurements. In contrast to just
printing out the ID of the checkpointed container, Podman will now print
out JSON:

 # podman container checkpoint --latest --print-stats
 {
     "podman_checkpoint_duration": 360749,
     "container_statistics": [
         {
             "Id": "25244244bf2efbef30fb6857ddea8cb2e5489f07eb6659e20dda117f0c466808",
             "runtime_checkpoint_duration": 177222,
             "criu_statistics": {
                 "freezing_time": 100657,
                 "frozen_time": 60700,
                 "memdump_time": 8162,
                 "memwrite_time": 4224,
                 "pages_scanned": 20561,
                 "pages_written": 2129
             }
         }
     ]
 }

The output contains 'podman_checkpoint_duration' which contains the
number of microseconds Podman required to create the checkpoint. The
output also includes 'runtime_checkpoint_duration' which is the time
the runtime needed to checkpoint that specific container. Each container
also includes 'criu_statistics' which displays the timing information
collected by CRIU.

Signed-off-by: Adrian Reber <areber@redhat.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/libpod/oci_conmon_linux.go b/libpod/oci_conmon_linux.go
index db906fabb..305d73d75 100644
--- a/libpod/oci_conmon_linux.go
+++ b/libpod/oci_conmon_linux.go
@@ -760,9 +760,9 @@ func (r *ConmonOCIRuntime) AttachResize(ctr *Container, newSize define.TerminalS
 }
 
 // CheckpointContainer checkpoints the given container.
-func (r *ConmonOCIRuntime) CheckpointContainer(ctr *Container, options ContainerCheckpointOptions) error {
+func (r *ConmonOCIRuntime) CheckpointContainer(ctr *Container, options ContainerCheckpointOptions) (int64, error) {
 	if err := label.SetSocketLabel(ctr.ProcessLabel()); err != nil {
-		return err
+		return 0, err
 	}
 	// imagePath is used by CRIU to store the actual checkpoint files
 	imagePath := ctr.CheckpointPath()
@@ -802,14 +802,25 @@ func (r *ConmonOCIRuntime) CheckpointContainer(ctr *Container, options Container
 	}
 	runtimeDir, err := util.GetRuntimeDir()
 	if err != nil {
-		return err
+		return 0, err
 	}
 	if err = os.Setenv("XDG_RUNTIME_DIR", runtimeDir); err != nil {
-		return errors.Wrapf(err, "cannot set XDG_RUNTIME_DIR")
+		return 0, errors.Wrapf(err, "cannot set XDG_RUNTIME_DIR")
 	}
 	args = append(args, ctr.ID())
 	logrus.Debugf("the args to checkpoint: %s %s", r.path, strings.Join(args, " "))
-	return utils.ExecCmdWithStdStreams(os.Stdin, os.Stdout, os.Stderr, nil, r.path, args...)
+
+	runtimeCheckpointStarted := time.Now()
+	err = utils.ExecCmdWithStdStreams(os.Stdin, os.Stdout, os.Stderr, nil, r.path, args...)
+
+	runtimeCheckpointDuration := func() int64 {
+		if options.PrintStats {
+			return time.Since(runtimeCheckpointStarted).Microseconds()
+		}
+		return 0
+	}()
+
+	return runtimeCheckpointDuration, err
 }
 
 func (r *ConmonOCIRuntime) CheckConmonRunning(ctr *Container) (bool, error) {