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From: Arjan van de Ven <arjan@infradead.org>
To: "Frédéric Weisbecker" <fweisbec@gmail.com>
Cc: mingo@elte.hu, linux-kernel@vger.kernel.org
Subject: Re: [patch] fix printk format typo in boot ftracer.
Date: Sat, 4 Oct 2008 17:24:49 -0700	[thread overview]
Message-ID: <20081004172449.58e53afd@infradead.org> (raw)
In-Reply-To: <c62985530810041358p1cc361b1te89894cedcd7e3b3@mail.gmail.com>

On Sat, 4 Oct 2008 22:58:12 +0200
"Frédéric Weisbecker" <fweisbec@gmail.com> wrote:

> > -               ret = trace_seq_printf(s, "[%5ld.%06ld] initcall %s
> > "
> > +               ret = trace_seq_printf(s, "[%5ld.%09ld] initcall %s
> > " "returned %d after %lld msecs\n",
> >                                          rettime.tv_sec,
> >                                          rettime.tv_nsec,
> 
> I picked these formats from the printk.c time formatting. But you're
> right, 09 would give us the whole nano precision.

it's more than precision, it's correctness.

doing "0.%02i" will do
0.100  if you pass it 100 and
0.10   if you pass it 10

and most off the time, except the first 0.1 seconds, you'll be passing
it 9 digits, but the first 0.1 seconds.. the %06 will just give really
incorrect results.



-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org

  reply	other threads:[~2008-10-05  0:25 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-10-04 20:42 [patch] fix printk format typo in boot ftracer Arjan van de Ven
2008-10-04 20:58 ` Frédéric Weisbecker
2008-10-05  0:24   ` Arjan van de Ven [this message]
2008-10-05  9:51     ` Ingo Molnar
2008-10-05 11:36     ` Frédéric Weisbecker

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