Rename track_iotiming GUC to track_io_timing.

This spelling seems significantly more readable to me.

doc/src/sgml/config.sgml

@@ -4288,10 +4288,10 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
       </listitem>
      </varlistentry>
 
-     <varlistentry id="guc-track-iotiming" xreflabel="track_iotiming">
+     <varlistentry id="guc-track-io-timing" xreflabel="track_io_timing">
-      <term><varname>track_iotiming</varname> (<type>boolean</type>)</term>
+      <term><varname>track_io_timing</varname> (<type>boolean</type>)</term>
       <indexterm>
-       <primary><varname>track_iotiming</> configuration parameter</primary>
+       <primary><varname>track_io_timing</> configuration parameter</primary>
       </indexterm>
       <listitem>
        <para>
@@ -4299,7 +4299,8 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
         default, because it will repeatedly query the operating system for
         the current time, which may cause significant overhead on some
         platforms.  You can use the <xref linkend="pgtesttiming"> tool to
-        measure the overhead of timing on your system.  Timing information is
+        measure the overhead of timing on your system.
+        I/O timing information is
         displayed in <xref linkend="pg-stat-database-view">, in the output of
         <xref linkend="sql-explain"> when the <literal>BUFFERS</> option is
         used, and by <xref linkend="pgstatstatements">.  Only superusers can

doc/src/sgml/monitoring.sgml

@@ -155,7 +155,7 @@ postgres: <replaceable>user</> <replaceable>database</> <replaceable>host</> <re
   </para>
 
   <para>
-   The parameter <xref linkend="guc-track-iotiming"> enables monitoring
+   The parameter <xref linkend="guc-track-io-timing"> enables monitoring
    of block read and write times.
   </para>
 

doc/src/sgml/pgstatstatements.sgml

@@ -161,7 +161,7 @@
       <entry></entry>
       <entry>
         Total time the statement spent reading blocks, in milliseconds
-        (if <xref linkend="guc-track-iotiming"> is enabled, otherwise zero)
+        (if <xref linkend="guc-track-io-timing"> is enabled, otherwise zero)
       </entry>
      </row>
 
@@ -171,7 +171,7 @@
       <entry></entry>
       <entry>
         Total time the statement spent writing blocks, in milliseconds
-        (if <xref linkend="guc-track-iotiming"> is enabled, otherwise zero)
+        (if <xref linkend="guc-track-io-timing"> is enabled, otherwise zero)
       </entry>
      </row>
 

src/backend/storage/buffer/bufmgr.c

@@ -67,7 +67,7 @@
 bool		zero_damaged_pages = false;
 int			bgwriter_lru_maxpages = 100;
 double		bgwriter_lru_multiplier = 2.0;
-bool		track_iotiming = false;
+bool		track_io_timing = false;
 
 /*
  * How many buffers PrefetchBuffer callers should try to stay ahead of their
@@ -441,12 +441,12 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 			instr_time	io_start,
 						io_time;
 
-			if (track_iotiming)
+			if (track_io_timing)
 				INSTR_TIME_SET_CURRENT(io_start);
 
 			smgrread(smgr, forkNum, blockNum, (char *) bufBlock);
 
-			if (track_iotiming)
+			if (track_io_timing)
 			{
 				INSTR_TIME_SET_CURRENT(io_time);
 				INSTR_TIME_SUBTRACT(io_time, io_start);
@@ -1938,7 +1938,7 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 	buf->flags &= ~BM_JUST_DIRTIED;
 	UnlockBufHdr(buf);
 
-	if (track_iotiming)
+	if (track_io_timing)
 		INSTR_TIME_SET_CURRENT(io_start);
 
 	smgrwrite(reln,
@@ -1947,7 +1947,7 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 			  (char *) BufHdrGetBlock(buf),
 			  false);
 
-	if (track_iotiming)
+	if (track_io_timing)
 	{
 		INSTR_TIME_SET_CURRENT(io_time);
 		INSTR_TIME_SUBTRACT(io_time, io_start);

src/backend/utils/misc/guc.c

@@ -1019,11 +1019,11 @@ static struct config_bool ConfigureNamesBool[] =
 		NULL, NULL, NULL
 	},
 	{
-		{"track_iotiming", PGC_SUSET, STATS_COLLECTOR,
+		{"track_io_timing", PGC_SUSET, STATS_COLLECTOR,
-			gettext_noop("Collects timing information for database IO activity."),
+			gettext_noop("Collects timing statistics for database I/O activity."),
 			NULL
 		},
-		&track_iotiming,
+		&track_io_timing,
 		false,
 		NULL, NULL, NULL
 	},

src/backend/utils/misc/postgresql.conf.sample

@@ -425,7 +425,7 @@
 
 #track_activities = on
 #track_counts = on
-#track_iotiming = off
+#track_io_timing = off
 #track_functions = none			# none, pl, all
 #track_activity_query_size = 1024 	# (change requires restart)
 #update_process_title = on

src/include/storage/bufmgr.h

@@ -48,7 +48,7 @@ extern PGDLLIMPORT int NBuffers;
 extern bool zero_damaged_pages;
 extern int	bgwriter_lru_maxpages;
 extern double bgwriter_lru_multiplier;
-extern bool track_iotiming;
+extern bool track_io_timing;
 extern int	target_prefetch_pages;
 
 /* in buf_init.c */