From: Andres Freund <andres@anarazel.de>
Date: Fri, 7 Apr 2023 20:24:26 +0000 (-0700)
Subject: Improve IO accounting for temp relation writes
X-Git-Url: http://git.postgresql.org/gitweb/-?a=commitdiff_plain;h=704261ecc694db11d9b5feb4f05f57778214ba2f;p=users%2Frhaas%2Fpostgres.git

Improve IO accounting for temp relation writes

Both pgstat_database and pgBufferUsage count IO timing for reads of temporary
relation blocks into local buffers. However, both failed to count write IO
timing for flushes of dirty local buffers. Fix.

Additionally, FlushRelationBuffers() seems to have omitted counting write
IO (both count and timing) stats for both pgstat_database and
pgBufferUsage. Fix.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20230321023451.7rzy4kjj2iktrg2r%40awork3.anarazel.de
---

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 908a8934bd..ef69f21adf 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -4062,6 +4062,8 @@ FlushRelationBuffers(Relation rel)
 {
 	int			i;
 	BufferDesc *bufHdr;
+	instr_time	io_start,
+				io_time;
 
 	if (RelationUsesLocalBuffers(rel))
 	{
@@ -4087,6 +4089,11 @@ FlushRelationBuffers(Relation rel)
 
 				PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
 
+				if (track_io_timing)
+					INSTR_TIME_SET_CURRENT(io_start);
+				else
+					INSTR_TIME_SET_ZERO(io_start);
+
 				smgrwrite(RelationGetSmgr(rel),
 						  BufTagGetForkNum(&bufHdr->tag),
 						  bufHdr->tag.blockNum,
@@ -4098,6 +4105,16 @@ FlushRelationBuffers(Relation rel)
 
 				pgstat_count_io_op(IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
 
+				if (track_io_timing)
+				{
+					INSTR_TIME_SET_CURRENT(io_time);
+					INSTR_TIME_SUBTRACT(io_time, io_start);
+					pgstat_count_buffer_write_time(INSTR_TIME_GET_MICROSEC(io_time));
+					INSTR_TIME_ADD(pgBufferUsage.blk_write_time, io_time);
+				}
+
+				pgBufferUsage.local_blks_written++;
+
 				/* Pop the error context stack */
 				error_context_stack = errcallback.previous;
 			}
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 3846d3eaca..3639296bc1 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -176,6 +176,8 @@ GetLocalVictimBuffer(void)
 	int			trycounter;
 	uint32		buf_state;
 	BufferDesc *bufHdr;
+	instr_time	io_start,
+				io_time;
 
 	ResourceOwnerEnlargeBuffers(CurrentResourceOwner);
 
@@ -239,6 +241,11 @@ GetLocalVictimBuffer(void)
 
 		PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
 
+		if (track_io_timing)
+			INSTR_TIME_SET_CURRENT(io_start);
+		else
+			INSTR_TIME_SET_ZERO(io_start);
+
 		/* And write... */
 		smgrwrite(oreln,
 				  BufTagGetForkNum(&bufHdr->tag),
@@ -252,6 +259,15 @@ GetLocalVictimBuffer(void)
 
 		/* Temporary table I/O does not use Buffer Access Strategies */
 		pgstat_count_io_op(IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
+
+		if (track_io_timing)
+		{
+			INSTR_TIME_SET_CURRENT(io_time);
+			INSTR_TIME_SUBTRACT(io_time, io_start);
+			pgstat_count_buffer_write_time(INSTR_TIME_GET_MICROSEC(io_time));
+			INSTR_TIME_ADD(pgBufferUsage.blk_write_time, io_time);
+		}
+
 		pgBufferUsage.local_blks_written++;
 	}