diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index 1a65c5f..0cf9216 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -99,9 +99,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 #include "srv0mon.h"
 #include "srv0srv.h"
 #include "srv0start.h"
-#ifdef UNIV_DEBUG
 #include "trx0purge.h"
-#endif /* UNIV_DEBUG */
 #include "trx0roll.h"
 #include "trx0sys.h"
 #include "trx0trx.h"
@@ -19064,6 +19062,53 @@ innodb_log_checksums_update(
 	mutex_exit(&log_sys->mutex);
 }
 
+/** Wakeup purge thread while turning down innodb_max_undo_log_size.
+@param[in]	thd	thread handle
+@param[in]	var	system variable
+@param[out]	var_ptr	current value
+@param[in]	save	immediate result from check function */
+static
+void
+innobase_max_undo_tablespace_update(
+	THD*				thd,
+	struct st_mysql_sys_var*	var,
+	void*				var_ptr,
+	const void*			save)
+{
+	ulonglong prev_val = srv_max_undo_log_size;
+	srv_max_undo_log_size = *static_cast<const ulonglong *>(save);
+
+	if (srv_undo_log_truncate
+	    && srv_max_undo_log_size < prev_val) {
+		/* Set the flag and wakeup purge thread */
+		purge_sys->undo_trunc.set_immediate_check();
+		srv_wake_purge_thread_if_not_active();
+	}
+}
+
+/** Wakeup purge thread while turning on innodb_undo_log_truncate
+@param[in]	thd	thread handle
+@param[in]	var	system variable
+@param[out]	var_ptr	current value
+@param[in]	save	immediate result from check function */
+static
+void
+innobase_undo_truncate_update(
+	THD*				thd,
+	struct st_mysql_sys_var*	var,
+	void*				var_ptr,
+	const void*			save)
+{
+	bool prev_val = srv_undo_log_truncate;
+	srv_undo_log_truncate = *static_cast<const bool *>(save);
+
+	if (srv_undo_log_truncate && !prev_val) {
+		/* Set the flag and wakeup purge thread */
+		purge_sys->undo_trunc.set_immediate_check();
+		srv_wake_purge_thread_if_not_active();
+	}
+}
+
 static SHOW_VAR innodb_status_variables_export[]= {
 	{"Innodb", (char*) &show_innodb_vars, SHOW_FUNC, SHOW_SCOPE_GLOBAL},
 	{NullS, NullS, SHOW_LONG, SHOW_SCOPE_GLOBAL}
@@ -19751,7 +19796,7 @@ static MYSQL_SYSVAR_ULONGLONG(max_undo_log_size, srv_max_undo_log_size,
   PLUGIN_VAR_OPCMDARG,
   "Maximum size of UNDO tablespace in MB (If UNDO tablespace grows"
   " beyond this size it will be truncated in due course). ",
-  NULL, NULL,
+  NULL, innobase_max_undo_tablespace_update,
   1024 * 1024 * 1024L,
   10 * 1024 * 1024L,
   ~0ULL, 0);
@@ -19766,7 +19811,7 @@ static MYSQL_SYSVAR_ULONG(purge_rseg_truncate_frequency,
 static MYSQL_SYSVAR_BOOL(undo_log_truncate, srv_undo_log_truncate,
   PLUGIN_VAR_OPCMDARG,
   "Enable or Disable Truncate of UNDO tablespace.",
-  NULL, NULL, FALSE);
+  NULL, innobase_undo_truncate_update, FALSE);
 
 /* Alias for innodb_undo_logs, this config variable is deprecated. */
 static MYSQL_SYSVAR_ULONG(rollback_segments, srv_undo_logs,
diff --git a/storage/innobase/include/trx0purge.h b/storage/innobase/include/trx0purge.h
index 8917169..150e915 100644
--- a/storage/innobase/include/trx0purge.h
+++ b/storage/innobase/include/trx0purge.h
@@ -332,6 +332,23 @@ namespace undo {
 			       != s_fix_up_spaces.end());
 		}
 
+		/* Set the flag to indicate that the purge thread need to check
+		undo tablespace immediately. */
+		void set_immediate_check(void)
+		{
+			undo_trunc_check = true;
+		}
+
+		/** Return the value of flag and then clear it */
+		bool need_immediate_check(void) {
+			bool ret = undo_trunc_check;
+
+			/* Reset the flag */
+			undo_trunc_check = false;
+
+			return (ret);
+		}
+
 		/** Get local rseg purge truncate frequency
 		@return rseg purge truncate frequency. */
 		ulint get_rseg_truncate_frequency() const
@@ -377,6 +394,10 @@ namespace undo {
 
 		/** List of UNDO tablespace(s) to truncate. */
 		static undo_spaces_t	s_spaces_to_truncate;
+
+		/** True if the purge thread need to check undo tablespace
+		immediately */
+		bool		undo_trunc_check;
 	public:
 		/** Undo tablespaces that were truncated at startup */
 		static undo_spaces_t	s_fix_up_spaces;
diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index 508e86b..352de8c 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -2614,7 +2614,8 @@ srv_do_purge(
 
 		n_pages_purged = trx_purge(
 			n_use_threads, srv_purge_batch_size,
-			(++count % rseg_truncate_frequency) == 0);
+			(++count % rseg_truncate_frequency) == 0
+			|| purge_sys->undo_trunc.need_immediate_check());
 
 		*n_total_purged += n_pages_purged;