Improve IO accounting for temp relation writes

anarazel · anarazel · commit 704261ecc694 · 2023-04-07T13:24:26.000-07:00
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
@@ -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
@@ -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++;
 	}
 
