linux-kernel - Re: [patch] fix printk format typo in boot ftracer.

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Date:	Sat, 4 Oct 2008 17:24:49 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	"Frédéric Weisbecker" <fweisbec@...il.com>
Cc:	mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [patch] fix printk format typo in boot ftracer.

On Sat, 4 Oct 2008 22:58:12 +0200
"Frédéric Weisbecker" <fweisbec@...il.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, 
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