diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
index c8d81b00089d..e5161e8f9915 100644
--- a/tools/perf/util/debug.c
+++ b/tools/perf/util/debug.c
@@ -46,6 +46,17 @@ int dump_printf(const char *fmt, ...)
 	return ret;
 }
 
+#ifdef NO_NEWT_SUPPORT
+void ui__warning(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfprintf(stderr, format, args);
+	va_end(args);
+}
+#endif
+
 static int dump_printf_color(const char *fmt, const char *color, ...)
 {
 	va_list args;
diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index 7b514082bbaf..ca35fd66b5df 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -35,4 +35,6 @@ int ui_helpline__show_help(const char *format, va_list ap);
 #include "ui/progress.h"
 #endif
 
+void ui__warning(const char *format, ...) __attribute__((format(printf, 1, 2)));
+
 #endif	/* __PERF_DEBUG_H */
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 3d5604739493..3ae69550fa0b 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -852,6 +852,24 @@ done:
 	flush_sample_queue(self, ops);
 out_err:
 	ui_progress__delete(progress);
+
+	if (ops->lost == event__process_lost &&
+	    self->hists.stats.total_lost != 0) {
+		ui__warning("Processed %Lu events and LOST %Lu!\n\n"
+			    "Check IO/CPU overload!\n\n",
+			    self->hists.stats.total_period,
+			    self->hists.stats.total_lost);
+	}
+	
+	if (self->hists.stats.nr_unknown_events != 0) {
+		ui__warning("Found %u unknown events!\n\n"
+			    "Is this an older tool processing a perf.data "
+			    "file generated by a more recent tool?\n\n"
+			    "If that is not the case, consider "
+			    "reporting to linux-kernel@vger.kernel.org.\n\n",
+			    self->hists.stats.nr_unknown_events);
+	}
+		
 	return err;
 }
 
diff --git a/tools/perf/util/ui/util.c b/tools/perf/util/ui/util.c
index 056c69521a38..7b5a8926624e 100644
--- a/tools/perf/util/ui/util.c
+++ b/tools/perf/util/ui/util.c
@@ -104,10 +104,24 @@ out_destroy_form:
 	return rc;
 }
 
-static const char yes[] = "Yes", no[] = "No";
+static const char yes[] = "Yes", no[] = "No",
+		  warning_str[] = "Warning!", ok[] = "Ok";
 
 bool ui__dialog_yesno(const char *msg)
 {
 	/* newtWinChoice should really be accepting const char pointers... */
 	return newtWinChoice(NULL, (char *)yes, (char *)no, (char *)msg) == 1;
 }
+
+void ui__warning(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	if (use_browser > 0)
+		newtWinMessagev((char *)warning_str, (char *)ok,
+				(char *)format, args);
+	else
+		vfprintf(stderr, format, args);
+	va_end(args);
+}