v6-0001-Use-timing-GUCs-on-pgstat_prepare_io_time-functio.patch

From e439ddc128c9b9ea1e2832f339e872c27d308499 Mon Sep 17 00:00:00 2001
From: Nazir Bilal Yavuz <byavuz81@gmail.com>
Date: Tue, 12 Dec 2023 10:33:55 +0300
Subject: [PATCH v6 1/6] Use timing GUCs on pgstat_prepare_io_time function

---
 src/backend/storage/buffer/bufmgr.c    | 10 +++++-----
 src/backend/storage/buffer/localbuf.c  |  4 ++--
 src/backend/storage/smgr/md.c          |  4 ++--
 src/backend/utils/activity/pgstat_io.c | 13 +++++++++++--
 4 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index f7c67d504c..a652907fc9 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1143,7 +1143,7 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 		MemSet((char *) bufBlock, 0, BLCKSZ);
 	else
 	{
-		instr_time	io_start = pgstat_prepare_io_time();
+		instr_time	io_start = pgstat_prepare_io_time(track_io_timing);
 
 		smgrread(smgr, forkNum, blockNum, bufBlock);
 
@@ -2070,7 +2070,7 @@ ExtendBufferedRelShared(BufferManagerRelation bmr,
 		}
 	}
 
-	io_start = pgstat_prepare_io_time();
+	io_start = pgstat_prepare_io_time(track_io_timing);
 
 	/*
 	 * Note: if smgrzeroextend fails, we will end up with buffers that are
@@ -3523,7 +3523,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
 	 */
 	bufToWrite = PageSetChecksumCopy((Page) bufBlock, buf->tag.blockNum);
 
-	io_start = pgstat_prepare_io_time();
+	io_start = pgstat_prepare_io_time(track_io_timing);
 
 	/*
 	 * bufToWrite is either the shared buffer or a copy, as appropriate.
@@ -4181,7 +4181,7 @@ FlushRelationBuffers(Relation rel)
 
 				PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
 
-				io_start = pgstat_prepare_io_time();
+				io_start = pgstat_prepare_io_time(track_io_timing);
 
 				smgrwrite(RelationGetSmgr(rel),
 						  BufTagGetForkNum(&bufHdr->tag),
@@ -5614,7 +5614,7 @@ IssuePendingWritebacks(WritebackContext *wb_context, IOContext io_context)
 	sort_pending_writebacks(wb_context->pending_writebacks,
 							wb_context->nr_pending);
 
-	io_start = pgstat_prepare_io_time();
+	io_start = pgstat_prepare_io_time(track_io_timing);
 
 	/*
 	 * Coalesce neighbouring writes, but nothing else. For that we iterate
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index aebcf146b4..903ea97b85 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -246,7 +246,7 @@ GetLocalVictimBuffer(void)
 
 		PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
 
-		io_start = pgstat_prepare_io_time();
+		io_start = pgstat_prepare_io_time(track_io_timing);
 
 		/* And write... */
 		smgrwrite(oreln,
@@ -411,7 +411,7 @@ ExtendBufferedRelLocal(BufferManagerRelation bmr,
 		}
 	}
 
-	io_start = pgstat_prepare_io_time();
+	io_start = pgstat_prepare_io_time(track_io_timing);
 
 	/* actually extend relation */
 	smgrzeroextend(bmr.smgr, fork, first_block, extend_by, false);
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index fdecbad170..62b2e79106 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -1172,7 +1172,7 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
 		ereport(DEBUG1,
 				(errmsg_internal("could not forward fsync request because request queue is full")));
 
-		io_start = pgstat_prepare_io_time();
+		io_start = pgstat_prepare_io_time(track_io_timing);
 
 		if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
 			ereport(data_sync_elevel(ERROR),
@@ -1569,7 +1569,7 @@ mdsyncfiletag(const FileTag *ftag, char *path)
 		need_to_close = true;
 	}
 
-	io_start = pgstat_prepare_io_time();
+	io_start = pgstat_prepare_io_time(track_io_timing);
 
 	/* Sync the file. */
 	result = FileSync(file, WAIT_EVENT_DATA_FILE_SYNC);
diff --git a/src/backend/utils/activity/pgstat_io.c b/src/backend/utils/activity/pgstat_io.c
index 490d5a9ab7..7263a80c72 100644
--- a/src/backend/utils/activity/pgstat_io.c
+++ b/src/backend/utils/activity/pgstat_io.c
@@ -92,14 +92,23 @@ pgstat_count_io_op_n(IOObject io_object, IOContext io_context, IOOp io_op, uint3
 	have_iostats = true;
 }
 
+/*
+ * Prepares the io_time for pgstat_count_io_op_time() function. This returns
+ * the current time if the 'track_time_guc' is true, otherwise returns zero.
+ */
 instr_time
-pgstat_prepare_io_time(void)
+pgstat_prepare_io_time(bool track_time_guc)
 {
 	instr_time	io_start;
 
-	if (track_io_timing)
+	if (track_time_guc)
 		INSTR_TIME_SET_CURRENT(io_start);
 	else
+
+		/*
+		 * If the time won't be tracked, there is no need to set io_start but
+		 * compiler complains about uninitialized use. So, set it to zero.
+		 */
 		INSTR_TIME_SET_ZERO(io_start);
 
 	return io_start;
-- 
2.43.0