linux-kernel - Re: [PATCH] ftracetest: Replace usleep with sleep 0.000001

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Message-ID: <549A1043.30003@hitachi.com>
Date:	Wed, 24 Dec 2014 10:00:51 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Michael Ellerman <mpe@...erman.id.au>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ftracetest: Replace usleep with sleep 0.000001

(2014/12/23 16:08), Michael Ellerman wrote:
> On Tue, 2014-12-23 at 13:21 +0900, Namhyung Kim wrote:
>> On Sat, Dec 20, 2014 at 05:07:25PM -0500, Steven Rostedt wrote:
>>> On Sat, 20 Dec 2014 21:42:13 +0100
>>> Pavel Machek <pavel@....cz> wrote:
>>>
>>>> On Wed 2014-12-10 15:38:27, Michael Ellerman wrote:
>>>>> usleep is a Fedoraism, it's not generally available on Debian based
>>>>> systems AFAICS.
>>>>>
>>>>> GNU sleep accepts a floating point argument, so use that instead.
>>>>>
>>>>> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
>>>>
>>>> Could ftrace user interface be enhanced not to need random delays?
>>>>
>>>
>>> Not sure what you are talking about. These "random delays" are not for
>>> the interface, but instead to force some events to happen and to make
>>> sure they did.
>>>
>>> As the subject states, this is for "ftracetest" which is the selftests
>>> for ftrace.
>>>
>>> The usleep is basically a "do something to trigger events", and we
>>> don't want to wait long in doing it.
>>
>> Right.  AFAIK what ftracetest expects is a scheduler event so it
>> doesn't need to be the [u]sleep.
> 
> Would /bin/true work in that case?

As other scripts doing, just (echo "forked") would be enough. It forks
sub shell and wait for that.
Please check test.d/kprobe/kprobe_args.tc

Thanks!


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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