To: john stultz <johnstul@us.ibm.com>
Cc: lkml <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
       Steven Rostedt <rostedt@goodmis.org>,
       Roman Zippel <zippel@linux-m68k.org>
Subject: Re: [PATCH] correct inconsistent ntp interval/tick_length usage
In-Reply-To: Your message of "Wed, 23 Jan 2008 18:38:53 PST."
             <1201142334.6383.40.camel@localhost.localdomain>
From: Valdis.Kletnieks@vt.edu
References: <1201142334.6383.40.camel@localhost.localdomain>
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Date: Thu, 24 Jan 2008 04:14:33 -0500
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On Wed, 23 Jan 2008 18:38:53 PST, john stultz said:
> I recently noticed on one of my boxes that when synched with an NTP
> server, the drift value reported for the system was ~283ppm. While in
> some cases, clock hardware can be that bad, it struck me as unusual as
> the system was using the acpi_pm clocksource, which is one of the more
> trustworthy and accurate clocksources on x86 hardware.
> 
> I brought up another system and let it sync to the same NTP server, and
> I noticed a similar 280some ppm drift.

So I got curious, and dropped the patch onto my workstation - 24-rc8-mm1 x86_64
and it applied just fine with an offset reported.

Before the patch, the drift was reported as 140.67 or so.
After, it's sitting at -0.681.

Am running with hpet clocksource rather than acpi_pm, which probably explains
the 140 I see rather than the 280 John saw....

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