linux-kernel - Re: [PATCH v2 22/32] selftests/ftrace: Add ringbuffer size changing testcase

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Date:   Fri, 24 Aug 2018 19:18:36 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Shuah Khan <shuah@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 22/32] selftests/ftrace: Add ringbuffer size changing
 testcase

On Fri, 17 Aug 2018 01:39:34 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> 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@...nel.org>

I'm fine with this, but one day I need to port over some of my other
tests. I have a test that stresses the ring buffer size (basically
checks to see if it can cause an oom). I need to port that to
selftests. But for now...

Acked-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

But, one more thing..

> ---
>  .../ftrace/test.d/00basic/ringbuffer_size.tc       |   21 ++++++++++++++++++++
>  1 file changed, 21 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..9224f33b3194
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/00basic/ringbuffer_size.tc
> @@ -0,0 +1,21 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Change the ringbuffer size

Should add:

 # flags: instance

As this works for instances as well.

-- Steve

> +
> +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