Re: AllocSetReset improvement

Tom Lane wrote:
> Bruce Momjian  writes:
> > Patch applied.  Thanks.  (The first if == NULL test was already in CVS).
> 
> The first if == NULL test was the only part I wanted to apply ...
> I do not think this patch is a performance win in general.

Attached is the part I backed out of CVS.

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: aset.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/utils/mmgr/aset.c,v
retrieving revision 1.60
retrieving revision 1.61
diff -c -c -r1.60 -r1.61
*** aset.c	14 May 2005 20:29:13 -0000	1.60
--- aset.c	4 Jun 2005 20:14:12 -0000	1.61
***************
*** 399,404 ****
--- 399,415 ----
  	if (block == NULL)
  		return;
  
+ 	/*
+ 	 * When blocks list has only "keeper" block and freeptr of the block
+ 	 * is initial value, the context is not used from last reset.
+ 	 */
+ 	if (block == set->keeper && block->next == NULL)
+ 	{
+ 		char	   *datastart = ((char *) block) + ALLOC_BLOCKHDRSZ;
+ 		if (block->freeptr == datastart)
+ 			return;
+ 	}
+ 
  	/* Clear chunk freelists */
  	MemSetAligned(set->freelist, 0, sizeof(set->freelist));