linux-kernel - Re: [PATCH] shrink printk timestamp field

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Date:	Mon, 01 Sep 2008 11:31:27 +0300
From:	Benny Halevy <bhalevy@...asas.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Joe Korty <joe.korty@...r.com>, "mingo@...e.hu" <mingo@...e.hu>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] shrink printk timestamp field

On Aug. 30, 2008, 20:16 +0300, Andrew Morton <akpm@...ux-foundation.org> wrote:
> On Sat, 30 Aug 2008 10:38:08 -0400 Joe Korty <joe.korty@...r.com> wrote:
> 
>> On Fri, Aug 29, 2008 at 07:35:40PM -0400, Andrew Morton wrote:
>>> On Wed, 27 Aug 2008 11:17:59 -0400 Joe Korty <joe.korty@...r.com> wrote:
>>>
>>>> Shrink the printk timestamp field.
>>>>
>>>> Keep the printk timestamp from occupying more of the
>>>> scarce, 80-column console line space than it really needs.
>>>>
>>> This is a significant loss in utility.
>>>
>>> [   16.817285] md: Autodetecting RAID arrays.
>>> [   16.817288] md: Scanned 0 and added 0 devices.
>>> [   16.817290] md: autorun ...
>>> [   16.817292] md: ... autorun DONE.
>>>
>>> This not-terribly-fast machine can emit printks into the log buffer
>>> within two microseconds.  That's a pretty useful ad-hoc timing
>>> factility.
>>>
>>> This patch will reduce the precision by a factor of five hundred.
>> I was looking at it from the point of view of finding out where the
>> boot process was too slow.  For that millisecs is enough.  I am not
>> sure where knowing printk output to the microsec would be useful for
>> solving anything.
>>
> 
> Of course it's useful.  If you're working on performance or latency in
> a disk, network or USB driver, microsecond resolution is about right.

How about supporting a configurable format string either by .config
and/or in runtime, e.g. given by a command line parameter?

Benny

> 
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