[PATCH v3 20/28] selftests/ftrace: Add ringbuffer size changing testcase

[Masami Hiramatsu]

Add a testcase for changing ringbuffer size. This tests
not only ringbuffer size but also tests the imbalance
per-cpu buffer size change too.

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 Changes in v3:
 - Run test on an instance too.
---
 .../ftrace/test.d/00basic/ringbuffer_size.tc       |   22 ++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/ringbuffer_size.tc

diff --git a/tools/testing/selftests/ftrace/test.d/00basic/ringbuffer_size.tc b/tools/testing/selftests/ftrace/test.d/00basic/ringbuffer_size.tc
new file mode 100644
index 000000000000..ab70f0077c35
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/00basic/ringbuffer_size.tc
@@ -0,0 +1,22 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Change the ringbuffer size
+# flags: instance
+
+rb_size_test() {
+ORIG=`cat buffer_size_kb`
+
+expr $ORIG / 2 > buffer_size_kb
+
+expr $ORIG \* 2 > buffer_size_kb
+
+echo $ORIG > buffer_size_kb
+}
+
+rb_size_test
+
+: "If per-cpu buffer is supported, imbalance it"
+if [ -d per_cpu/cpu0 ]; then
+  cd per_cpu/cpu0
+  rb_size_test
+fi