diff --git a/tbsetup/mapper.in b/tbsetup/mapper.in
index 6f5c155007a715238491786b89aafe24c07bb9e2..3c6a5f839fd6ec2c2eedd48e81dac314181adfad 100644
--- a/tbsetup/mapper.in
+++ b/tbsetup/mapper.in
@@ -51,13 +51,14 @@ sub usage ()
     print STDERR " -l   - Use rspec v2 instead of the text file format\n";
     exit($WRAPPER_FAILED);
 }
-my $optlist    = "dvunfprqczxm:ko:al";
+my $optlist    = "dvunfprqczxm:ko:alt";
 my $verbose    = 0;
 my $debug      = 0;
 my $fixmode    = 0;
 my $updating   = 0;
 my $impotent   = 0;
 my $precheck   = 0;
+my $toponly    = 0;
 my $prepass    = 0;
 my $alloconly  = 0;
 my $outfile;
@@ -147,6 +148,10 @@ if (defined($options{"d"})) {
 if (defined($options{"u"})) {
     $updating = 1;
 }
+if (defined($options{"t"})) {
+    $toponly = 1;
+    $quiet   = 1;
+}
 if (defined($options{"n"})) {
     $impotent = 1;
 }
@@ -170,7 +175,8 @@ if (defined($options{"r"})) {
 	fatal("Cannot use regression mode on main DB");
     }
     $regression = 1;
-    $clear      = 1;
+    $clear      = 1
+	if (!defined($options{"t"}));
     $fixmode    = 1;
     TBDebugTimeStampsOn();
     $usecurrent = 1
@@ -248,7 +254,8 @@ exit(0);
 
 sub MapperWrapper()
 {
-    chat("Starting the new and improved mapper wrapper.\n");
+    chat("Starting the new and improved mapper wrapper.\n")
+	if (!$toponly);
 
     # Need to do this cause libvtop will add them again.
     # Must be done before nodes are released.
@@ -261,12 +268,13 @@ sub MapperWrapper()
 	fatal("Could not create vtop structure for $experiment");
     }
     TBDebugTimeStamp("Create libvtop ended");
+
     TBDebugTimeStamp("vtopgen started");
     $vtop->CreateVtop() == 0
 	or fatal("Could not create vtop for $experiment");
     TBDebugTimeStamp("vtopgen finished");
     
-    if (!$impotent && ($updating || $clear)) {
+    if (!$impotent && !$toponly && ($updating || $clear)) {
 	if ($clear) {
 	    chat("Freeing reserved nodes ...\n");
 	    system("export NORELOAD=1; $NFREE -x -a $pid $eid") == 0
@@ -403,7 +411,7 @@ sub AssignLoop()
 	$currentrun++;
     }
     GatherAssignStats($pid, $eid, %{ $vtop->exptstats() })
-	if (! ($impotent || $alloconly));
+	if (! ($impotent || $alloconly || $regression || $toponly));
     TBDebugTimeStamp("mapper loop finished");
     return 0;
 }
@@ -424,6 +432,28 @@ sub RunAssign($$)
     }
     my $assignexitcode = 0;
 
+    #
+    # Now generate a vtop file and dump it to a file.
+    #
+    if (! open(VTOPFILE, "> $vtopfile")) {
+	tberror("Could not open $vtopfile: $!\n");
+	return -1;
+    }
+    my $reslibvtop;
+    if ($userspec == 1) {
+	$reslibvtop = $vtop->PrintRspec(*VTOPFILE);
+    }
+    else {
+	$reslibvtop = $vtop->PrintTop(*VTOPFILE);
+    }
+    if ($reslibvtop != 0) {
+	tberror("Could not print vtop file for $experiment\n");
+	return -1;
+    }
+    close(VTOPFILE);
+    return 0
+	if ($toponly);
+
     # Debugging hack for regression mode. Avoid really long assign runs.
     if ($regression && $noassign) {
 	if (! -e "assign.log") {
@@ -501,26 +531,6 @@ sub RunAssign($$)
     }
     TBDebugTimeStamp("ptopgen finished");
 
-    #
-    # Now generate a vtop file and dump it to a file.
-    #
-    if (! open(VTOPFILE, "> $vtopfile")) {
-	tberror("Could not open $vtopfile: $!\n");
-	return -1;
-    }
-    my $reslibvtop;
-    if ($userspec == 1) {
-	$reslibvtop = $vtop->PrintRspec(*VTOPFILE);
-    }
-    else {
-	$reslibvtop = $vtop->PrintTop(*VTOPFILE);
-    }
-    if ($reslibvtop != 0) {
-	tberror("Could not print vtop file for $experiment\n");
-	return -1;
-    }
-    close(VTOPFILE);
-
     if (! ($impotent || $regression || $alloconly)) {
 	if ($experiment->Update({"maximum_nodes" => $vtop->maximum_nodes(),
 				 "minimum_nodes" => $vtop->minimum_nodes(),