func runPutObjectPartBenchmark(b *testing.B, obj ObjectLayer, partSize int) {
	var err error
	// obtains random bucket name.
	bucket := getRandomBucketName()
	object := getRandomObjectName()

	// create bucket.
	err = obj.MakeBucket(context.Background(), bucket, MakeBucketOptions{})
	if err != nil {
		b.Fatal(err)
	}

	objSize := 128 * humanize.MiByte