Merge lp:~laurynas-biveinis/percona-server/bug1238039 into lp:percona-server/5.6

[Laurynas Biveinis]

Fix bug 1238039: a regression in page cleaner thread furious flushing support. When page cleaner thread was allowed to skip sleeps in the case of empty free lists or large checkpoint age, each iteration was no longer required to take 1 second, the server could have been considered inactive if the sleep was skipped and the page cleaner iteration was short. Which had an effect of performing idle server flush list flushing for innodb I/O capacity-number of pages instead of a busy server adaptive flushing.

The fix is to maintain the timestamp of the last last_activity update
in the main page cleaner thread loop. Then, perform busy server tasks
not only if the server activity has advanced, but also if it has not
advanced for less than 1 second.

http://jenkins.percona.com/job/percona-server-5.6-param/425/

[George Ormond Lorch III (gl-az)]

review: Approve (g2)

=== modified file 'Percona-Server/storage/innobase/buf/buf0flu.cc'
--- Percona-Server/storage/innobase/buf/buf0flu.cc	2013-12-02 11:15:58 +0000
+++ Percona-Server/storage/innobase/buf/buf0flu.cc	2013-12-02 11:15:59 +0000
@@ -2645,6 +2645,7 @@
 	ulint	next_loop_time = ut_time_ms() + 1000;
 	ulint	n_flushed = 0;
 	ulint	last_activity = srv_get_activity_count();
+	ulint	last_activity_time = ut_time_ms();
 
 	ut_ad(!srv_read_only_mode);
 
@@ -2666,6 +2667,7 @@
 	while (srv_shutdown_state == SRV_SHUTDOWN_NONE) {
 
 		ulint	page_cleaner_sleep_time;
+		ibool	server_active;
 
 		srv_current_thread_priority = srv_cleaner_thread_priority;
 
@@ -2683,8 +2685,15 @@
 
 		next_loop_time = ut_time_ms() + page_cleaner_sleep_time;
 
-		if (srv_check_activity(last_activity)) {
-			last_activity = srv_get_activity_count();
+		server_active = srv_check_activity(last_activity);
+		if (server_active
+		    || ut_time_ms() - last_activity_time < 1000) {
+
+			if (server_active) {
+
+				last_activity = srv_get_activity_count();
+				last_activity_time = ut_time_ms();
+			}
 
 			/* Flush pages from flush_list if required */
 			n_flushed += page_cleaner_flush_pages_if_needed();