linux-kernel - [PATCH] tools lib traceevent: Add filter on task CPU id

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Date:	Tue, 12 Jul 2016 09:33:06 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH] tools lib traceevent: Add filter on task CPU id


Add a 'CPU' special field to allow the filter in trace-cmd report
to filter on the task's CPU.

By adding a special field 'CPU' (all caps) the user can now
filter out tasks based on which CPU they are on. This is useful when
filtering out (or in) a bunch of threads.

  -F 'CPU == 0'

Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 tools/lib/traceevent/parse-filter.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index 88cccea3ca99..7c214ceb9386 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -28,11 +28,16 @@
 #include "event-utils.h"
 
 #define COMM "COMM"
+#define CPU "CPU"
 
 static struct format_field comm = {
 	.name = "COMM",
 };
 
+static struct format_field cpu = {
+	.name = "CPU",
+};
+
 struct event_list {
 	struct event_list	*next;
 	struct event_format	*event;
@@ -382,14 +387,17 @@ create_arg_item(struct event_format *event, const char *token,
 		/* Consider this a field */
 		field = pevent_find_any_field(event, token);
 		if (!field) {
-			if (strcmp(token, COMM) != 0) {
+			/* If token is 'COMM' or 'CPU' then it is special */
+			if (strcmp(token, COMM) == 0) {
+				field = &comm;
+			} else if (strcmp(token, CPU) == 0) {
+				field = &cpu;
+			} else {
 				/* not a field, Make it false */
 				arg->type = FILTER_ARG_BOOLEAN;
 				arg->boolean.value = FILTER_FALSE;
 				break;
 			}
-			/* If token is 'COMM' then it is special */
-			field = &comm;
 		}
 		arg->type = FILTER_ARG_FIELD;
 		arg->field.field = field;
@@ -1718,6 +1726,10 @@ get_value(struct event_format *event,
 		return (unsigned long)name;
 	}
 
+	/* Handle our dummy "cpu" field */
+	if (field == &cpu)
+		return record->cpu;
+
 	pevent_read_number_field(field, record->data, &val);
 
 	if (!(field->flags & FIELD_IS_SIGNED))
-- 
1.9.3