diff options
Diffstat (limited to 'src/include/storage/buf_internals.h')
| -rw-r--r-- | src/include/storage/buf_internals.h | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h index 4effa0d740f..18239176b8e 100644 --- a/src/include/storage/buf_internals.h +++ b/src/include/storage/buf_internals.h @@ -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 $ * *------------------------------------------------------------------------- */ @@ -87,6 +87,17 @@ typedef struct buftag ) /* + * 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. * * Note: buf_hdr_lock must be held to examine or change the tag, flags, @@ -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, |