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authorBruce Momjian <bruce@momjian.us>2005-06-04 20:14:12 +0000
committerBruce Momjian <bruce@momjian.us>2005-06-04 20:14:12 +0000
commit3cf1fd3263ee4fd585df80fb235c855b8a97426d (patch)
tree8a3f98050d3a26528a0f563648394e814ce88b96 /src
parente18e8f873594fd4ff2f12e734a624102d3ef1e39 (diff)
downloadpostgresql-3cf1fd3263ee4fd585df80fb235c855b8a97426d.tar.gz
postgresql-3cf1fd3263ee4fd585df80fb235c855b8a97426d.zip
Tom Lane <tgl@sss.pgh.pa.us> writes:
> a_ogawa <a_ogawa@hi-ho.ne.jp> writes: > > It is a reasonable idea. However, the majority part of MemSet was not > > able to be avoided by this idea. Because the per-tuple contexts are used > > at the early stage of executor. > > Drat. Well, what about changing that? We could introduce additional > contexts or change the startup behavior so that the ones that are > frequently reset don't have any data in them unless you are working > with pass-by-ref values inside the inner loop. That might be possible. However, I think that we should change only aset.c about this article. I thought further: We can check whether context was used from the last reset even when blocks list is not empty. Please see attached patch. The effect of the patch that I measured is as follows: o Execution time that executed the SQL ten times. (1)Linux(CPU: Pentium III, Compiler option: -O2) - original: 24.960s - patched : 23.114s (2)Linux(CPU: Pentium 4, Compiler option: -O2) - original: 8.730s - patched : 7.962s (3)Solaris(CPU: Ultra SPARC III, Compiler option: -O2) - original: 37.0s - patched : 33.7s Atsushi Ogawa (a_ogawa)
Diffstat (limited to 'src')
-rw-r--r--src/backend/utils/mmgr/aset.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
index 4f60b186c27..f7550929f1f 100644
--- a/src/backend/utils/mmgr/aset.c
+++ b/src/backend/utils/mmgr/aset.c
@@ -11,7 +11,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/mmgr/aset.c,v 1.60 2005/05/14 20:29:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mmgr/aset.c,v 1.61 2005/06/04 20:14:12 momjian Exp $
*
* NOTE:
* This is a new (Feb. 05, 1999) implementation of the allocation set
@@ -399,6 +399,17 @@ AllocSetReset(MemoryContext context)
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));