Index: bufmgr.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v
retrieving revision 1.228
diff -u -3 -p -r1.228 bufmgr.c
--- bufmgr.c	1 Jan 2008 19:45:51 -0000	1.228
+++ bufmgr.c	15 May 2008 20:56:38 -0000
@@ -42,6 +42,7 @@
 #include "storage/smgr.h"
 #include "utils/resowner.h"
 #include "pgstat.h"
+#include "pg_trace.h"
 
 
 /* Note: these two macros only work on shared buffers, not local ones! */
@@ -171,6 +172,7 @@ ReadBuffer_common(Relation reln, BlockNu
 	if (isExtend)
 		blockNum = smgrnblocks(reln->rd_smgr);
 
+	TRACE_POSTGRESQL_BUFFER_READ_START(blockNum, reln->rd_node.spcNode, reln->rd_node.dbNode, reln->rd_node.relNode, isLocalBuf);
 	pgstat_count_buffer_read(reln);
 
 	if (isLocalBuf)
@@ -200,12 +202,16 @@ ReadBuffer_common(Relation reln, BlockNu
 	{
 		if (!isExtend)
 		{
+			TRACE_POSTGRESQL_BUFFER_HIT();
 			/* Just need to update stats before we exit */
 			pgstat_count_buffer_hit(reln);
 
 			if (VacuumCostActive)
 				VacuumCostBalance += VacuumCostPageHit;
 
+			TRACE_POSTGRESQL_BUFFER_READ_DONE(blockNum,
+				 reln->rd_node.spcNode, reln->rd_node.dbNode,
+				 reln->rd_node.relNode, isLocalBuf, found);
 			return BufferDescriptorGetBuffer(bufHdr);
 		}
 
@@ -257,6 +263,7 @@ ReadBuffer_common(Relation reln, BlockNu
 			} while (!StartBufferIO(bufHdr, true));
 		}
 	}
+	TRACE_POSTGRESQL_BUFFER_MISS();
 
 	/*
 	 * if we have gotten to this point, we have allocated a buffer for the
@@ -324,6 +331,9 @@ ReadBuffer_common(Relation reln, BlockNu
 	if (VacuumCostActive)
 		VacuumCostBalance += VacuumCostPageMiss;
 
+	TRACE_POSTGRESQL_BUFFER_READ_DONE(blockNum, reln->rd_node.spcNode,
+		reln->rd_node.dbNode, reln->rd_node.relNode, isLocalBuf, found);
+
 	return BufferDescriptorGetBuffer(bufHdr);
 }
 
@@ -466,6 +476,11 @@ BufferAlloc(Relation reln,
 			 * happens to be trying to split the page the first one got from
 			 * StrategyGetBuffer.)
 			 */
+
+			TRACE_POSTGRESQL_DIRTY_BUFFER_WRITE_START(blockNum,
+			  reln->rd_node.spcNode, reln->rd_node.dbNode,
+			  reln->rd_node.relNode);
+
 			if (LWLockConditionalAcquire(buf->content_lock, LW_SHARED))
 			{
 				/*
@@ -488,6 +503,11 @@ BufferAlloc(Relation reln,
 				/* OK, do the I/O */
 				FlushBuffer(buf, NULL);
 				LWLockRelease(buf->content_lock);
+
+				TRACE_POSTGRESQL_DIRTY_BUFFER_WRITE_DONE(
+				  blockNum, reln->rd_node.spcNode,
+				  reln->rd_node.dbNode, reln->rd_node.relNode,
+				  (oldFlags & BM_HINT_BITS_TEST));
 			}
 			else
 			{
@@ -1734,6 +1754,10 @@ FlushBuffer(volatile BufferDesc *buf, SM
 	buf->flags &= ~BM_JUST_DIRTIED;
 	UnlockBufHdr(buf);
 
+	TRACE_POSTGRESQL_BUFFER_WRITE_START(buf->tag.blockNum,
+		 reln->smgr_rnode.spcNode, reln->smgr_rnode.dbNode,
+		 reln->smgr_rnode.relNode);
+
 	smgrwrite(reln,
 			  buf->tag.blockNum,
 			  (char *) BufHdrGetBlock(buf),
@@ -1741,6 +1765,10 @@ FlushBuffer(volatile BufferDesc *buf, SM
 
 	BufferFlushCount++;
 
+	TRACE_POSTGRESQL_BUFFER_WRITE_DONE(buf->tag.blockNum,
+		 reln->smgr_rnode.spcNode, reln->smgr_rnode.dbNode,
+		 reln->smgr_rnode.relNode, (buf->flags & BM_HINT_BITS_TEST));
+
 	/*
 	 * Mark the buffer as clean (unless BM_JUST_DIRTIED has become set) and
 	 * end the io_in_progress state.
@@ -2155,7 +2183,7 @@ SetBufferCommitInfoNeedsSave(Buffer buff
 		Assert(bufHdr->refcount > 0);
 		if (!(bufHdr->flags & BM_DIRTY) && VacuumCostActive)
 			VacuumCostBalance += VacuumCostPageDirty;
-		bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED);
+		bufHdr->flags |= (BM_DIRTY | BM_JUST_DIRTIED | BM_HINT_BITS_TEST);
 		UnlockBufHdr(bufHdr);
 	}
 }
@@ -2492,7 +2520,7 @@ TerminateBufferIO(volatile BufferDesc *b
 	Assert(buf->flags & BM_IO_IN_PROGRESS);
 	buf->flags &= ~(BM_IO_IN_PROGRESS | BM_IO_ERROR);
 	if (clear_dirty && !(buf->flags & BM_JUST_DIRTIED))
-		buf->flags &= ~(BM_DIRTY | BM_CHECKPOINT_NEEDED);
+		buf->flags &= ~(BM_DIRTY | BM_CHECKPOINT_NEEDED | BM_HINT_BITS_TEST);
 	buf->flags |= set_flag_bits;
 
 	UnlockBufHdr(buf);
Index: buf_internals.h
===================================================================
RCS file: /projects/cvsroot/pgsql/src/include/storage/buf_internals.h,v
retrieving revision 1.95
diff -u -3 -p -r1.95 buf_internals.h
--- buf_internals.h	1 Jan 2008 19:45:58 -0000	1.95
+++ buf_internals.h	15 May 2008 20:59:42 -0000
@@ -36,6 +36,7 @@
 #define BM_JUST_DIRTIED			(1 << 5)		/* dirtied since write started */
 #define BM_PIN_COUNT_WAITER		(1 << 6)		/* have waiter for sole pin */
 #define BM_CHECKPOINT_NEEDED	(1 << 7)		/* must write for checkpoint */
+#define BM_HINT_BITS_TEST	(1 << 8)		/* test effect of writes due to hint bits */
 
 typedef bits16 BufFlags;