Increase amount of shared buffers initdb tries to allocate to 4000,
and add logic to try max_fsm_pages up to 200000, plus accompanying minor
docs changes.

Author: adunstan

doc/src/sgml/config.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.40 2005/12/23 00:38:03 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.41 2005/12/27 23:54:01 adunstan Exp $
 -->
 <chapter Id="runtime-config">
   <title>Server Configuration</title>
@@ -672,7 +672,7 @@ SET ENABLE_SEQSCAN TO OFF;
       <listitem>
        <para>
         Sets the number of shared memory buffers used by the database
-        server. The default is typically 1000, but may be less if your
+        server. The default is typically 4000, but may be less if your
         kernel settings will not support it (as determined during
         <application>initdb</>).  Each buffer is 8192 bytes, unless a
         different value of <symbol>BLCKSZ</symbol> was chosen when building
@@ -867,8 +867,10 @@ SET ENABLE_SEQSCAN TO OFF;
         Sets the maximum number of disk pages for which free space will
         be tracked in the shared free-space map.  Six bytes of shared memory
         are consumed for each page slot.  This setting must be more than
-        16 * <varname>max_fsm_relations</varname>.  The default is 20000.
-        This option can only be set at server start.
+        16 * <varname>max_fsm_relations</varname>.  The default is 20000,
+		but <application>initdb</> will try to set it as close as possible 
+		to 200000, depending on the amount of available memory.
+		This option can only be set at server start.
        </para>
       </listitem>
      </varlistentry>

src/bin/initdb/initdb.c

@@ -42,7 +42,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  * Portions taken from FreeBSD.
  *
- * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.101 2005/12/09 15:51:14 petere Exp $
+ * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.102 2005/12/27 23:54:01 adunstan Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -120,6 +120,7 @@ static int	output_errno = 0;
 /* defaults */
 static int	n_connections = 10;
 static int	n_buffers = 50;
+static int  n_fsm_pages = 20000; 
 
 /*
  * Warning messages for authentication methods
@@ -1083,6 +1084,13 @@ set_null_conf(void)
 	}
 }
 
+/*
+ * max_fsm_pages setting used in both the shared_buffers and max_connections
+ * tests. 
+ */
+
+#define TEST_FSM(x) ( (x) > 1000 ? 50 * (x) : 20000 )
+
 /*
  * check how many connections we can sustain
  */
@@ -1100,12 +1108,17 @@ test_connections(void)
 
 	for (i = 0; i < len; i++)
 	{
+		int test_buffs = conns[i] * 5;
+		int test_max_fsm =  TEST_FSM(test_buffs);
+
 		snprintf(cmd, sizeof(cmd),
 				 "%s\"%s\" -boot -x0 %s "
+				 "-c max_fsm_pages=%d "
 				 "-c shared_buffers=%d -c max_connections=%d template1 "
 				 "< \"%s\" > \"%s\" 2>&1%s",
 				 SYSTEMQUOTE, backend_exec, boot_options,
-				 conns[i] * 5, conns[i],
+				 test_max_fsm,
+				 test_buffs, conns[i],
 				 DEVNULL, DEVNULL, SYSTEMQUOTE);
 		status = system(cmd);
 		if (status == 0)
@@ -1125,22 +1138,30 @@ static void
 test_buffers(void)
 {
 	char		cmd[MAXPGPATH];
-	static const int bufs[] = {1000, 900, 800, 700, 600, 500,
-	400, 300, 200, 100, 50};
+	static const int bufs[] = {
+	  4000, 3500, 3000, 2500, 2000, 1500,
+	  1000, 900, 800, 700, 600, 500,
+	  400, 300, 200, 100, 50
+	};
 	static const int len = sizeof(bufs) / sizeof(int);
 	int			i,
-				status;
+				status,
+	            test_max_fsm_pages;
 
-	printf(_("selecting default shared_buffers ... "));
+	printf(_("selecting default shared_buffers/max_fsm_pages ... "));
 	fflush(stdout);
 
 	for (i = 0; i < len; i++)
 	{
+		test_max_fsm_pages = TEST_FSM(bufs[i]);
+
 		snprintf(cmd, sizeof(cmd),
 				 "%s\"%s\" -boot -x0 %s "
+				 "-c max_fsm_pages=%d "
 				 "-c shared_buffers=%d -c max_connections=%d template1 "
 				 "< \"%s\" > \"%s\" 2>&1%s",
 				 SYSTEMQUOTE, backend_exec, boot_options,
+				 test_max_fsm_pages,
 				 bufs[i], n_connections,
 				 DEVNULL, DEVNULL, SYSTEMQUOTE);
 		status = system(cmd);
@@ -1150,8 +1171,9 @@ test_buffers(void)
 	if (i >= len)
 		i = len - 1;
 	n_buffers = bufs[i];
+	n_fsm_pages = test_max_fsm_pages;
 
-	printf("%d\n", n_buffers);
+	printf("%d/%d\n", n_buffers, n_fsm_pages);
 }
 
 /*
@@ -1177,6 +1199,9 @@ setup_config(void)
 	snprintf(repltok, sizeof(repltok), "shared_buffers = %d", n_buffers);
 	conflines = replace_token(conflines, "#shared_buffers = 1000", repltok);
 
+	snprintf(repltok, sizeof(repltok), "max_fsm_pages = %d", n_fsm_pages);
+	conflines = replace_token(conflines, "#max_fsm_pages = 20000", repltok);
+
 #if DEF_PGPORT != 5432
 	snprintf(repltok, sizeof(repltok), "#port = %d", DEF_PGPORT);
 	conflines = replace_token(conflines, "#port = 5432", repltok);