Reduce the memcpy call from SearchCatCache

Hi,
Here is the oprofile results of pgbench.

CPU: P4 / Xeon with 2 hyper-threads, speed 2793.55 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events
with a unit mask of 0x01 (mandatory) count 100000
samples  %        app name                 symbol name
134521    6.8312  ipmi_si                  (no symbols)
94515     4.7996  vmlinux                  schedule
52609     2.6716  postgres                 AllocSetAlloc
39659     2.0140  postgres                 base_yyparse
34605     1.7573  vmlinux                  mwait_idle
33234     1.6877  vmlinux                  _spin_lock
31353     1.5922  libc-2.3.4.so            memcpy

I think that the performance improves if the call frequency of memcpy
is reduced. I measured the place where postgres used memcpy.
(Test program is pgbench -t 4000)

 total-size avg-size caller
------------------------------------------------------------------------
  636185  111968560      176 catcache.c:1129
   68236   18436197      270 xlog.c:947
    3909   13822874     3536 xlog.c:940
   20003    3520528      176 catcache.c:1376
   56010    2071477       36 pgstat.c:2288
  125524    1902864       15 dynahash.c:948
   20001    1760088       88 setrefs.c:205

catcache.c:1129 is memcpy at SearchCatCache, and catcache.c:1376
is memcpy at SearchCatCacheList.

    memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));

Attached patch is reduce the memcpy calls from SearchCatCache
and SearchCatCacheList. This patch directly uses cache->cc_skey
in looking for hash table.
Here is an effect of the patch.

original: Counted GLOBAL_POWER_EVENTS events
samples  %        app name                 symbol name
31353     1.5922  libc-2.3.4.so            memcpy

patched: Counted GLOBAL_POWER_EVENTS events
samples  %        app name                 symbol name
20629     1.0684  libc-2.3.4.so            memcpy

---
Atsushi Ogawa

*** ./src/backend/utils/cache/catcache.c.orig    2009-07-06 22:06:52.000000000 +0900
--- ./src/backend/utils/cache/catcache.c    2009-07-06 13:51:48.000000000 +0900
***************
*** 1124,1140 ****

      /*
       * initialize the search key information
       */
!     memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
!     cur_skey[0].sk_argument = v1;
!     cur_skey[1].sk_argument = v2;
!     cur_skey[2].sk_argument = v3;
!     cur_skey[3].sk_argument = v4;

      /*
       * find the hash bucket in which to look for the tuple
       */
!     hashValue = CatalogCacheComputeHashValue(cache, cache->cc_nkeys, cur_skey);
      hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);

      /*
--- 1124,1141 ----

      /*
       * initialize the search key information
+      * use cache->cc_skey directly in looking for hash table
       */
!     cache->cc_skey[0].sk_argument = v1;
!     cache->cc_skey[1].sk_argument = v2;
!     cache->cc_skey[2].sk_argument = v3;
!     cache->cc_skey[3].sk_argument = v4;

      /*
       * find the hash bucket in which to look for the tuple
       */
!     hashValue = CatalogCacheComputeHashValue(cache, cache->cc_nkeys,
!         cache->cc_skey);
      hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);

      /*
***************
*** 1160,1166 ****
          HeapKeyTest(&ct->tuple,
                      cache->cc_tupdesc,
                      cache->cc_nkeys,
!                     cur_skey,
                      res);
          if (!res)
              continue;
--- 1161,1167 ----
          HeapKeyTest(&ct->tuple,
                      cache->cc_tupdesc,
                      cache->cc_nkeys,
!                     cache->cc_skey,
                      res);
          if (!res)
              continue;
***************
*** 1222,1227 ****
--- 1223,1234 ----
       */
      relation = heap_open(cache->cc_reloid, AccessShareLock);

+     /*
+      * We need copy ScanKey data, because systable_beginscan changes
+      * the ScanKey data.
+      */
+     memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
+
      scandesc = systable_beginscan(relation,
                                    cache->cc_indexoid,
                                    IndexScanOK(cache, cur_skey),
***************
*** 1371,1389 ****

      /*
       * initialize the search key information
       */
!     memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
!     cur_skey[0].sk_argument = v1;
!     cur_skey[1].sk_argument = v2;
!     cur_skey[2].sk_argument = v3;
!     cur_skey[3].sk_argument = v4;

      /*
       * compute a hash value of the given keys for faster search.  We don't
       * presently divide the CatCList items into buckets, but this still lets
       * us skip non-matching items quickly most of the time.
       */
!     lHashValue = CatalogCacheComputeHashValue(cache, nkeys, cur_skey);

      /*
       * scan the items until we find a match or exhaust our list
--- 1378,1396 ----

      /*
       * initialize the search key information
+      * use cache->cc_skey directly in looking for hash table
       */
!     cache->cc_skey[0].sk_argument = v1;
!     cache->cc_skey[1].sk_argument = v2;
!     cache->cc_skey[2].sk_argument = v3;
!     cache->cc_skey[3].sk_argument = v4;

      /*
       * compute a hash value of the given keys for faster search.  We don't
       * presently divide the CatCList items into buckets, but this still lets
       * us skip non-matching items quickly most of the time.
       */
!     lHashValue = CatalogCacheComputeHashValue(cache, nkeys, cache->cc_skey);

      /*
       * scan the items until we find a match or exhaust our list
***************
*** 1410,1416 ****
          HeapKeyTest(&cl->tuple,
                      cache->cc_tupdesc,
                      nkeys,
!                     cur_skey,
                      res);
          if (!res)
              continue;
--- 1417,1423 ----
          HeapKeyTest(&cl->tuple,
                      cache->cc_tupdesc,
                      nkeys,
!                     cache->cc_skey,
                      res);
          if (!res)
              continue;
***************
*** 1460,1465 ****
--- 1467,1478 ----

          relation = heap_open(cache->cc_reloid, AccessShareLock);

+         /*
+          * We need copy ScanKey data, because systable_beginscan changes
+          * the ScanKey data.
+          */
+         memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
+
          scandesc = systable_beginscan(relation,
                                        cache->cc_indexoid,
                                        true,