perf tools: Fix lost and unknown events handling

Fix it by explaining what can be happening and giving the number of processed
and lost events.

Also holler if unknown events were found, that can be due to processing a
perf.data file collected using a newer tool where newer events got added on
reporting using an older perf tool, that or a bug, so ask for a report to be
made.

Works on both --tui and --stdio.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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;

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 */

tools/perf/util/session.c

@@ -852,6 +852,24 @@ int __perf_session__process_events(struct perf_session *self,
 	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;
 }
 

tools/perf/util/ui/util.c

@@ -104,10 +104,24 @@ int ui__help_window(const char *text)
 	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);
+}