Subject: Re: [BUG] 2.6.0-test2 loses time on 486
From: john stultz <johnstul@us.ibm.com>
To: Mikael Pettersson <mikpe@csd.uu.se>
Cc: lkml <linux-kernel@vger.kernel.org>
In-Reply-To: <200307291734.h6THYhmp012585@harpo.it.uu.se>
References: <200307291734.h6THYhmp012585@harpo.it.uu.se>
Content-Type: text/plain
Organization: 
Message-Id: <1059505144.14761.55.camel@w-jstultz2.beaverton.ibm.com>
Mime-Version: 1.0
Date: 29 Jul 2003 11:59:06 -0700
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1224
Lines: 31

On Tue, 2003-07-29 at 10:34, Mikael Pettersson wrote:
> My old 486 test box is losing time at an alarming rate
> when running 2.6.0-test kernels. It loses almost 2 minutes
> per hour, less if it sits idle. This problem does not
> occur when it's running a 2.4 kernel.
> 
> There's nothing noteworthy in dmesg.
> 
> This has been going on since at least the 2.5.7x kernels,
> and possible also the 2.5.6x kernels. I strongly suspect
> a bug in the time-keeping changes in late 2.5 kernels.
> The 486 has no TSC, and I don't have an NTP server to
> keep my machines' times in sync.

Hmm.  Sounds like you're loosing interrupts. This can happen due to
poorly behaving drivers (disabling interrupts for too long), or odd
hardware. The change from HZ=100 to HZ=1000 probably made this more
visible on your box, so could you try setting HZ back to 100 and see if
that helps (you may still lose time, but at a much slower rate). 

Also what drivers are you running with?

thanks
-john


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/