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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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4
src/backend/storage/buffer/bufmgr.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.192 2005/08/08 19:44:22 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.193 2005/08/12 05:05:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -54,7 +54,7 @@
/* Note: these two macros only work on shared buffers, not local ones! */
#define BufHdrGetBlock(bufHdr) BufferBlockPointers[(bufHdr)->buf_id]
#define BufHdrGetBlock(bufHdr) ((Block) (BufferBlocks + ((Size) (bufHdr)->buf_id) * BLCKSZ))
#define BufferGetLSN(bufHdr) (*((XLogRecPtr*) BufHdrGetBlock(bufHdr)))
/* Note: this macro only works on local buffers, not shared ones! */