MDEV-27917 Some redo log diagnostics is always reported as 0

The InnoDB monitor counter log_sys.n_log_ios was almost removed in commit 685d958 (MDEV-14425). This counter was rather meaningless already since commit 30ea63b introduced a redo log group commit mechanism, and on the persistent memory interface there are no file system calls that could be counted. The only case when log_sys.n_log_ios was updated is when the log file was being read during crash recovery. Some related output in log_print() as well as the information_schema.innodb_metrics counter log_num_log_io are best removed.
MariaDB · Feb 22, 2022 · 934b2d6 · 934b2d6
1 parent 30b036d
commit 934b2d6
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diff --git a/mysql-test/suite/innodb/r/innodb_skip_innodb_is_tables.result b/mysql-test/suite/innodb/r/innodb_skip_innodb_is_tables.result
@@ -180,7 +180,6 @@ log_lsn_current	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0
 log_lsn_checkpoint_age	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Current LSN value minus LSN at last checkpoint
 log_lsn_buf_pool_oldest	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	The oldest modified block LSN in the buffer pool
 log_max_modified_age_async	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Maximum LSN difference; when exceeded, start asynchronous preflush
-log_num_log_io	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Number of log I/Os
 log_waits	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log waits due to small log buffer (innodb_log_waits)
 log_write_requests	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log write requests (innodb_log_write_requests)
 log_writes	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log writes (innodb_log_writes)

diff --git a/mysql-test/suite/innodb/r/monitor.result b/mysql-test/suite/innodb/r/monitor.result
@@ -146,7 +146,6 @@ log_lsn_current	disabled
 log_lsn_checkpoint_age	disabled
 log_lsn_buf_pool_oldest	disabled
 log_max_modified_age_async	disabled
-log_num_log_io	disabled
 log_waits	disabled
 log_write_requests	disabled
 log_writes	disabled

diff --git a/storage/innobase/include/log0log.h b/storage/innobase/include/log0log.h
@@ -99,11 +99,6 @@ void
 log_print(
 /*======*/
 	FILE*	file);	/*!< in: file where to print */
-/**********************************************************************//**
-Refreshes the statistics used to print per-second averages. */
-void
-log_refresh_stats(void);
-/*===================*/
 
 /** Offsets of a log file header */
 /* @{ */
@@ -240,16 +235,6 @@ struct log_t
   /** Log file */
   log_file_t log;
 
-	/** The fields involved in the log buffer flush @{ */
-
-	ulint		n_log_ios;	/*!< number of log i/os initiated thus
-					far */
-	ulint		n_log_ios_old;	/*!< number of log i/o's at the
-					previous printout */
-	time_t		last_printout_time;/*!< when log_print was last time
-					called */
-	/* @} */
-
 	/** Fields involved in checkpoints @{ */
 	lsn_t		log_capacity;	/*!< capacity of the log; if
 					the checkpoint age exceeds this, it is

diff --git a/storage/innobase/include/srv0mon.h b/storage/innobase/include/srv0mon.h
@@ -304,7 +304,6 @@ enum monitor_id_t {
 	MONITOR_LSN_CHECKPOINT_AGE,
 	MONITOR_OVLD_BUF_OLDEST_LSN,
 	MONITOR_OVLD_MAX_AGE_ASYNC,
-	MONITOR_LOG_IO,
 	MONITOR_OVLD_LOG_WAITS,
 	MONITOR_OVLD_LOG_WRITE_REQUEST,
 	MONITOR_OVLD_LOG_WRITES,

diff --git a/storage/innobase/log/log0log.cc b/storage/innobase/log/log0log.cc
@@ -126,12 +126,7 @@ void log_t::create()
   max_buf_free= buf_size / LOG_BUF_FLUSH_RATIO - LOG_BUF_FLUSH_MARGIN;
   set_check_flush_or_checkpoint();
 
-  n_log_ios_old= n_log_ios;
-  last_printout_time= time(NULL);
-
   last_checkpoint_lsn= FIRST_LSN;
-  n_log_ios= 0;
-  n_log_ios_old= 0;
   log_capacity= 0;
   max_modified_age_async= 0;
   max_checkpoint_age= 0;
@@ -1007,9 +1002,6 @@ log_print(
 /*======*/
 	FILE*	file)	/*!< in: file where to print */
 {
-	double	time_elapsed;
-	time_t	current_time;
-
 	log_sys.latch.rd_lock(SRW_LOCK_CALL);
 
 	const lsn_t lsn= log_sys.get_lsn();
@@ -1027,40 +1019,9 @@ log_print(
 		pages_flushed,
 		lsn_t{log_sys.last_checkpoint_lsn});
 
-	current_time = time(NULL);
-
-	time_elapsed = difftime(current_time,
-				log_sys.last_printout_time);
-
-	if (time_elapsed <= 0) {
-		time_elapsed = 1;
-	}
-
-	fprintf(file,
-		ULINTPF " pending chkp writes\n"
-		ULINTPF " log i/o's done, %.2f log i/o's/second\n",
-		log_sys.n_pending_checkpoint_writes,
-		log_sys.n_log_ios,
-		static_cast<double>(
-			log_sys.n_log_ios - log_sys.n_log_ios_old)
-		/ time_elapsed);
-
-	log_sys.n_log_ios_old = log_sys.n_log_ios;
-	log_sys.last_printout_time = current_time;
-
 	log_sys.latch.rd_unlock();
 }
 
-/**********************************************************************//**
-Refreshes the statistics used to print per-second averages. */
-void
-log_refresh_stats(void)
-/*===================*/
-{
-	log_sys.n_log_ios_old = log_sys.n_log_ios;
-	log_sys.last_printout_time = time(NULL);
-}
-
 /** Shut down the redo log subsystem. */
 void log_t::close()
 {

diff --git a/storage/innobase/log/log0recv.cc b/storage/innobase/log/log0recv.cc
@@ -3546,7 +3546,6 @@ static bool recv_scan_log(bool last_phase)
       if (source_offset + size > log_sys.file_size)
         size= static_cast<size_t>(log_sys.file_size - source_offset);
 
-      log_sys.n_log_ios++;
       if (dberr_t err= log_sys.log.read(source_offset,
                                         {log_sys.buf + recv_sys.len, size}))
       {

diff --git a/storage/innobase/srv/srv0mon.cc b/storage/innobase/srv/srv0mon.cc
@@ -800,11 +800,6 @@ static monitor_info_t	innodb_counter_info[] =
 	 MONITOR_EXISTING | MONITOR_DISPLAY_CURRENT),
 	 MONITOR_DEFAULT_START, MONITOR_OVLD_MAX_AGE_ASYNC},
 
-	{"log_num_log_io", "recovery", "Number of log I/Os",
-	 static_cast<monitor_type_t>(
-	 MONITOR_EXISTING | MONITOR_DISPLAY_CURRENT),
-	 MONITOR_DEFAULT_START, MONITOR_LOG_IO},
-
 	{"log_waits", "recovery",
 	 "Number of log waits due to small log buffer (innodb_log_waits)",
 	 static_cast<monitor_type_t>(
@@ -1706,10 +1701,6 @@ srv_mon_process_existing_counter(
 		value = log_sys.get_lsn();
 		break;
 
-	case MONITOR_LOG_IO:
-		value = log_sys.n_log_ios;
-		break;
-
         case MONITOR_OVLD_CHECKPOINTS:
 		value = log_sys.next_checkpoint_no;
 		break;

diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
@@ -711,8 +711,6 @@ static void srv_refresh_innodb_monitor_stats(time_t current_time)
 	btr_cur_n_non_sea_old = btr_cur_n_non_sea;
 #endif /* BTR_CUR_HASH_ADAPT */
 
-	log_refresh_stats();
-
 	buf_refresh_io_stats();
 
 	srv_n_rows_inserted_old = srv_stats.n_rows_inserted;

diff --git a/storage/rocksdb/mysql-test/rocksdb/r/innodb_i_s_tables_disabled.result b/storage/rocksdb/mysql-test/rocksdb/r/innodb_i_s_tables_disabled.result
@@ -162,7 +162,6 @@ log_lsn_current	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0
 log_lsn_checkpoint_age	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Current LSN value minus LSN at last checkpoint
 log_lsn_buf_pool_oldest	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	The oldest modified block LSN in the buffer pool
 log_max_modified_age_async	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Maximum LSN difference; when exceeded, start asynchronous preflush
-log_num_log_io	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	value	Number of log I/Os
 log_waits	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log waits due to small log buffer (innodb_log_waits)
 log_write_requests	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log write requests (innodb_log_write_requests)
 log_writes	recovery	0	NULL	NULL	NULL	0	NULL	NULL	NULL	NULL	NULL	NULL	NULL	0	status_counter	Number of log writes (innodb_log_writes)