+#if defined(USE_PAPI)
+" -aX CPU performance counter measurements using PAPI",
+" (use with the -s<file> option). X is one of:",
+"",
+/* " y - cycles", */
+" 1 - level 1 cache misses",
+" 2 - level 2 cache misses",
+" b - branch mispredictions",
+" s - stalled cycles",
+#endif