diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fdf6625..0c0f215 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -141,9 +141,12 @@ static CheckpointerShmemStruct *CheckpointerShmem;
 /*
  * GUC parameters
  */
+int			CheckPointerWriteDelay = 200;
 int			CheckPointTimeout = 300;
 int			CheckPointWarning = 30;
 double		CheckPointCompletionTarget = 0.5;
+double		CheckPointSmoothTarget = 0.0;
+double		CheckPointSmoothMargin = 0.0;
 
 /*
  * Flags set by interrupt handlers for later service in the main loop.
@@ -715,7 +718,7 @@ CheckpointWriteDelay(int flags, double progress)
 		 * Checkpointer and bgwriter are no longer related so take the Big
 		 * Sleep.
 		 */
-		pg_usleep(100000L);
+		pg_usleep(CheckPointerWriteDelay * 1000L);
 	}
 	else if (--absorb_counter <= 0)
 	{
@@ -742,14 +745,36 @@ IsCheckpointOnSchedule(double progress)
 {
 	XLogRecPtr	recptr;
 	struct timeval now;
-	double		elapsed_xlogs,
+	double		original_progress,
+			elapsed_xlogs,
 				elapsed_time;
 
 	Assert(ckpt_active);
 
-	/* Scale progress according to checkpoint_completion_target. */
-	progress *= CheckPointCompletionTarget;
+	/* This variable is used by smooth checkpoint schedule.*/
+	original_progress = progress * CheckPointCompletionTarget;
 
+	/* Scale progress according to checkpoint_completion_target and checkpoint_smooth_target. */
+	if(progress >= CheckPointSmoothTarget)
+	{
+		/* Normal checkpoint schedule. */
+		progress *= CheckPointCompletionTarget;
+	}
+	else
+	{
+		/*
+		 * Smooth checkpoint schedule.
+		 *
+		 * When initial checkpoint, it tends to be high IO road average
+		 * and slow executing transactions. This schedule reduces them
+		 * and improve IO responce. As 'progress' approximates CheckPointSmoothTarget,
+		 * it becomes near normal checkpoint schedule. If you want to more
+		 * smooth checkpoint schedule, you set higher CheckPointSmoothTarget.
+		 */
+		progress *= ((CheckPointSmoothTarget - progress) / CheckPointSmoothTarget) *
+				(CheckPointSmoothMargin + 1 - CheckPointCompletionTarget) +
+				CheckPointCompletionTarget;
+	}
 	/*
 	 * Check against the cached value first. Only do the more expensive
 	 * calculations once we reach the target previously calculated. Since
@@ -779,6 +804,14 @@ IsCheckpointOnSchedule(double progress)
 			ckpt_cached_elapsed = elapsed_xlogs;
 			return false;
 		}
+		else if (original_progress < elapsed_xlogs)
+		{
+			ckpt_cached_elapsed = elapsed_xlogs;
+
+			/* smooth checkpoint write */
+			pg_usleep(CheckPointerWriteDelay * 1000L);
+			return false;
+		}
 	}
 
 	/*
@@ -793,6 +826,14 @@ IsCheckpointOnSchedule(double progress)
 		ckpt_cached_elapsed = elapsed_time;
 		return false;
 	}
+	else if (original_progress < elapsed_time)
+	{
+		ckpt_cached_elapsed = elapsed_time;
+
+		/* smooth checkpoint write */
+		pg_usleep(CheckPointerWriteDelay * 1000L);
+		return false;
+	}
 
 	/* It looks like we're on schedule. */
 	return true;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea16c64..d41dc17 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2014,6 +2014,17 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
+		{"checkpointer_write_delay", PGC_SIGHUP, RESOURCES_CHECKPOINTER,
+			gettext_noop("checkpointer sleep time during dirty buffers write in checkpoint."),
+			NULL,
+			GUC_UNIT_MS
+		},
+		&CheckPointerWriteDelay,
+		200, 10, 10000,
+		NULL, NULL, NULL
+	},
+
+	{
 		{"wal_buffers", PGC_POSTMASTER, WAL_SETTINGS,
 			gettext_noop("Sets the number of disk-page buffers in shared memory for WAL."),
 			NULL,
@@ -2551,6 +2562,26 @@ static struct config_real ConfigureNamesReal[] =
 		NULL, NULL, NULL
 	},
 
+	{
+		{"checkpoint_smooth_target", PGC_SIGHUP, RESOURCES_CHECKPOINTER,
+			gettext_noop("Smooth control IO load between starting checkpoint and this target parameter in progress of checkpoint."),
+			NULL
+		},
+		&CheckPointSmoothTarget,
+		0.0, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
+	{
+		{"checkpoint_smooth_margin", PGC_SIGHUP, RESOURCES_CHECKPOINTER,
+		gettext_noop("More smooth control IO load between starting checkpoint and checkpoint_smooth_target."),
+		NULL
+		},
+		&CheckPointSmoothMargin,
+		0.0, 0.0, 1.0,
+		NULL, NULL, NULL
+	},
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, 0.0, 0.0, 0.0, NULL, NULL, NULL
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 0303ac7..b4d83f2 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -185,7 +185,10 @@
 #checkpoint_segments = 3		# in logfile segments, min 1, 16MB each
 #checkpoint_timeout = 5min		# range 30s-1h
 #checkpoint_completion_target = 0.5	# checkpoint target duration, 0.0 - 1.0
+#checkpoint_smooth_target = 0.0		# smooth checkpoint target, 0.0 - 1.0
+#checkpoint_smooth_margin = 0.0		# smooth checkpoint margin, 0.0 - 1.0
 #checkpoint_warning = 30s		# 0 disables
+#checkpointer_write_delay = 200ms	# 10-10000 milliseconds
 
 # - Archiving -
 
diff --git a/src/include/postmaster/bgwriter.h b/src/include/postmaster/bgwriter.h
index 46d3c26..8a441bc 100644
--- a/src/include/postmaster/bgwriter.h
+++ b/src/include/postmaster/bgwriter.h
@@ -21,9 +21,12 @@
 
 /* GUC options */
 extern int	BgWriterDelay;
+extern int	CheckPointerWriteDelay;
 extern int	CheckPointTimeout;
 extern int	CheckPointWarning;
 extern double CheckPointCompletionTarget;
+extern double CheckPointSmoothTarget;
+extern double CheckPointSmoothMargin;
 
 extern void BackgroundWriterMain(void) __attribute__((noreturn));
 extern void CheckpointerMain(void) __attribute__((noreturn));
diff --git a/src/include/utils/guc_tables.h b/src/include/utils/guc_tables.h
index 8dcdd4b..efc5ee4 100644
--- a/src/include/utils/guc_tables.h
+++ b/src/include/utils/guc_tables.h
@@ -63,6 +63,7 @@ enum config_group
 	RESOURCES_KERNEL,
 	RESOURCES_VACUUM_DELAY,
 	RESOURCES_BGWRITER,
+	RESOURCES_CHECKPOINTER,
 	RESOURCES_ASYNCHRONOUS,
 	WAL,
 	WAL_SETTINGS,