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Remove BufferBlockPointers array in favor of a base + (bufnum) * BLCKSZ

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computation.  On modern machines this is as fast if not faster, and we
don't have to clog the CPU's L2 cache with a tens-of-KB pointer array.
If we ever decide to adopt a more dynamic allocation method for shared
buffers, we'll probably have to revert this patch, but in the meantime
we might as well save a few bytes and nanoseconds.  Per Qingqing Zhou.
This commit is contained in:
Tom Lane
2005-08-12 05:05:51 +00:00
parent b609695b7a
commit 3ae7e4a33b
3 changed files with 7 additions and 28 deletions
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6
src/include/storage/bufmgr.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.94 2005/08/08 03:12:16 tgl Exp $
* $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.95 2005/08/12 05:05:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -33,7 +33,7 @@ extern int bgwriter_lru_maxpages;
extern int bgwriter_all_maxpages;
/* in buf_init.c */
extern DLLIMPORT Block *BufferBlockPointers;
extern DLLIMPORT char *BufferBlocks;
extern DLLIMPORT int32 *PrivateRefCount;
/* in localbuf.c */
@@ -107,7 +107,7 @@ extern DLLIMPORT int32 *LocalRefCount;
BufferIsLocal(buffer) ? \
LocalBufferBlockPointers[-(buffer) - 1] \
: \
BufferBlockPointers[(buffer) - 1] \
(Block) (BufferBlocks + ((Size) ((buffer) - 1)) * BLCKSZ) \
)
/*