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Split the buffer mapping table into multiple separately lockable

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partitions, as per discussion.  Passes functionality checks, but
I don't have any performance data yet.
This commit is contained in:
Tom Lane
2006-07-23 03:07:58 +00:00
parent 51ee9fa157
commit 10b9ca3d05
8 changed files with 198 additions and 75 deletions
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20
src/include/storage/buf_internals.h
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@@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.86 2006/03/31 23:32:07 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/buf_internals.h,v 1.87 2006/07/23 03:07:58 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -86,6 +86,17 @@ typedef struct buftag
(a).blockNum == (b).blockNum \
)
/*
* The shared buffer mapping table is partitioned to reduce contention.
* To determine which partition lock a given tag requires, compute the tag's
* hash code with BufTableHashCode(), then apply BufMappingPartitionLock().
* NB: NUM_BUFFER_PARTITIONS must be a power of 2!
*/
#define BufTableHashPartition(hashcode) \
((hashcode) % NUM_BUFFER_PARTITIONS)
#define BufMappingPartitionLock(hashcode) \
((LWLockId) (FirstBufMappingLock + BufTableHashPartition(hashcode)))
/*
* BufferDesc -- shared descriptor/state data for a single shared buffer.
*
@@ -182,9 +193,10 @@ extern void StrategyInitialize(bool init);
/* buf_table.c */
extern Size BufTableShmemSize(int size);
extern void InitBufTable(int size);
extern int BufTableLookup(BufferTag *tagPtr);
extern int BufTableInsert(BufferTag *tagPtr, int buf_id);
extern void BufTableDelete(BufferTag *tagPtr);
extern uint32 BufTableHashCode(BufferTag *tagPtr);
extern int BufTableLookup(BufferTag *tagPtr, uint32 hashcode);
extern int BufTableInsert(BufferTag *tagPtr, uint32 hashcode, int buf_id);
extern void BufTableDelete(BufferTag *tagPtr, uint32 hashcode);
/* localbuf.c */
extern BufferDesc *LocalBufferAlloc(Relation reln, BlockNumber blockNum,