linux-kernel - Re: Slow clock on AMD 740G chipset

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Date:	Fri, 24 Apr 2009 18:45:46 -0700
From:	David Rees <drees76@...il.com>
To:	Michael Tokarev <mjt@....msk.ru>
Cc:	Mika Tiainen <mikat@....fi>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: Slow clock on AMD 740G chipset

On Tue, Mar 24, 2009 at 10:34 AM, Michael Tokarev <mjt@....msk.ru> wrote:
> To refresh what has been said.  Several people observed slow clock
> on their - mostly AMD 780g, 740g and 690g-based systems with 2.6.28
> 2.6.27 kernels.  Slow to a point when ntpd wasn't successful to
> keep up with the drift.  It has been said that the motherboards are
> flaky or something and that the clocks has to be calibrated, for
> which there are known procedures available (adjtimex).  Which helped.
> Before the "calibration" the clock were off by ~15 minutes per day.

This is really weird.  I earlier posted to the thread saying things
were fine on a Fedora 10 2.6.27.9-159.fc10.x86_64 kernel.

Then mysteriously after a machine reboot to install new hardware[1] on
March 27th on kernel 2.6.27.19-170.2.35.fc10.x86_64 (previous running
kernel was the same), the clock started running slow to the tune of
ntpd resetting the time every 15-18 minutes forward about 2.3 seconds.

Fast forward to today (now running 2.6.29.1-30.fc10.x86_64) and the
clock is still running slow.

> So it seems that with 2.6.29, all the motherboards suddenly become
> non-flaky and the timers need no calibration anymore, working just
> fine.  Other operating systems and kernel versions also agree with
> this conclusion of 2.6.29.

I don't know - my system (GA-MA74GM-S2 mobo) is still broken.

[1] So the hardware I installed was a SATA SSD (OCZ Vertex). Ever
since then, the clock has been running fast.  Previously, the only
thing on the SATA bus was a DVD drive - it has two IDE drives, one
plugged in on board and the other into a Promise IDE card.

When doing so, the sata ports are now running in AHCI mode instead of
native mode.  I'll have to try switching later.

-Dave
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