From 3165151e17c10cdf22745bf3eeed938103f10911 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Sat, 4 Jun 2005 20:14:12 +0000 Subject: [PATCH] Tom Lane writes: > a_ogawa 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) --- src/backend/utils/mmgr/aset.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c index afbb57af68..dfe93b187d 100644 --- a/src/backend/utils/mmgr/aset.c +++ b/src/backend/utils/mmgr/aset.c @@ -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)); -- 2.39.5