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, 33 insertions, 1 deletions

diff --git a/cmd/podman/containers/checkpoint.go b/cmd/podman/containers/checkpoint.go
index 4fa72d520..d92bc3e5e 100644
--- a/cmd/podman/containers/checkpoint.go
+++ b/cmd/podman/containers/checkpoint.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/containers/common/pkg/completion"
 	"github.com/containers/podman/v3/cmd/podman/common"
@@ -40,6 +41,11 @@ var (
 
 var checkpointOptions entities.CheckpointOptions
 
+type checkpointStatistics struct {
+	PodmanDuration      int64                        `json:"podman_checkpoint_duration"`
+	ContainerStatistics []*entities.CheckpointReport `json:"container_statistics"`
+}
+
 func init() {
 	registry.Commands = append(registry.Commands, registry.CliCommand{
 		Command: checkpointCommand,
@@ -63,11 +69,19 @@ func init() {
 	flags.StringP("compress", "c", "zstd", "Select compression algorithm (gzip, none, zstd) for checkpoint archive.")
 	_ = checkpointCommand.RegisterFlagCompletionFunc("compress", common.AutocompleteCheckpointCompressType)
 
+	flags.BoolVar(
+		&checkpointOptions.PrintStats,
+		"print-stats",
+		false,
+		"Display checkpoint statistics",
+	)
+
 	validate.AddLatestFlag(checkpointCommand, &checkpointOptions.Latest)
 }
 
 func checkpoint(cmd *cobra.Command, args []string) error {
 	var errs utils.OutputErrors
+	podmanStart := time.Now()
 	if cmd.Flags().Changed("compress") {
 		if checkpointOptions.Export == "" {
 			return errors.Errorf("--compress can only be used with --export")
@@ -102,12 +116,30 @@ func checkpoint(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
+	podmanFinished := time.Now()
+
+	var statistics checkpointStatistics
+
 	for _, r := range responses {
 		if r.Err == nil {
-			fmt.Println(r.Id)
+			if checkpointOptions.PrintStats {
+				statistics.ContainerStatistics = append(statistics.ContainerStatistics, r)
+			} else {
+				fmt.Println(r.Id)
+			}
 		} else {
 			errs = append(errs, r.Err)
 		}
 	}
+
+	if checkpointOptions.PrintStats {
+		statistics.PodmanDuration = podmanFinished.Sub(podmanStart).Microseconds()
+		j, err := json.MarshalIndent(statistics, "", "    ")
+		if err != nil {
+			return err
+		}
+		fmt.Println(string(j))
+	}
+
 	return errs.PrintErrors()
 }