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Date: Mon, 22 Aug 2005 13:33:06 -0700
From: Jason Uhlenkott <jasonuhl@sgi.com>
To: "David S. Miller" <davem@davemloft.net>
Cc: tony.luck@intel.com, akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: CONFIG_PRINTK_TIME woes
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References: <20050821021322.3986dd4a.akpm@osdl.org> <20050821021616.6bbf2a14.akpm@osdl.org> <200508221742.j7MHgMJI020020@agluck-lia64.sc.intel.com> <20050822.132052.65406121.davem@davemloft.net>
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On Mon, Aug 22, 2005 at 01:20:52PM -0700, David S. Miller wrote:
> From: tony.luck@intel.com
> Date: Mon, 22 Aug 2005 10:42:22 -0700
> 
> > At the other extreme ... the current use of sched_clock() with
> > potentially nano-second resolution is way over the top.
> 
> Not really, when I'm debugging TCP events over gigabit
> these timestamps are exceptionally handy.

Yes, but how many of those figures are really significant?  I strongly
suspect that the overhead of printk() is high enough, even when we're
just spewing to the dmesg buffer and not the console, that we have a
lot more precision than accuracy at nanosecond resolution.