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

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Message-ID: <1418341176.20629.2.camel@ellerman.id.au>
Date:	Fri, 12 Dec 2014 10:39:36 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH] ftracetest: Replace usleep with sleep 0.000001

On Thu, 2014-12-11 at 14:12 +0900, Masami Hiramatsu wrote:
> Hi,
> 
> (2014/12/10 17:19), Namhyung Kim wrote:
> > Hi Michael,
> > 
> > On Wed, Dec 10, 2014 at 1:38 PM, Michael Ellerman <mpe@...erman.id.au> 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.
> > 
> > I tested it on busybox not Debian, sorry.  But it seems busybox's
> > sleep doesn't support floating point argument..
> > 
> >   / # ls -l `which sleep`
> >   lrwxrwxrwx     1  root     rooot       7 May 22  2014  /bin/sleep -> busybox
> > 
> >   / # sleep 0.1
> >   sleep: invalid number '0.1'
> 
> I also have same result. Basically, ftracetest should be able to run on busybox.

Yeah OK.

> So, I think we'd better check whether usleep is available, and if not, fallback
> to sleep like as below.
> 
>   if which usleep &> /dev/null; then
>     usleep 1
>   else
>     sleep 0.000001
>   fi

Why do we need to call (u)sleep anyway? It's generally a bad sign when tests
use sleep as it's asking for random timing related failures to creep in.

cheers


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