Index: tools/perf/view_halts.py
===================================================================
--- tools/perf/view_halts.py	(revision b813f53fc0dfce3e9f17e185d9b6d30753ed0409)
+++ tools/perf/view_halts.py	(revision 9bbbc8e937fa1f70fadbd73a682237ba1c6fff22)
@@ -12,4 +12,9 @@
 parser.add_argument('-o', '--output', dest='outfile', type=argparse.FileType('w'), default=None, help='output file with any image format extension such as .png or .svg; if none specified then plt.show() will be used')
 args = parser.parse_args()
+
+print("----- Processing Halts Output -----")
+if not args.outfile:
+	print("ERROR : no output file specified and interactive mode not supported", file=sys.stderr)
+	sys.exit(1)
 
 #--------------------------------------------------------------------------------
@@ -91,5 +96,5 @@
 #--------------------------------------------------------------------------------
 # setup plot
-dots_per_inch = 2000
+dots_per_inch = 200
 height_inches = 5
 width_inches = 12
@@ -121,7 +126,4 @@
 # do the plot
 plt.tight_layout()
-if not args.outfile:
-	plt.show()
-else:
-	print("saving figure image %s\n" % args.outfile.name)
-	plt.savefig(args.outfile.name)
+print("saving figure image %s\n" % args.outfile.name)
+plt.savefig(args.outfile.name)