Date: Mon, 27 Feb 2006 17:47:26 -0500 (EST)
From: Jason Baron <jbaron@redhat.com>
To: "Bill Rugolsky Jr." <brugolsky@telemetry-investments.com>
cc: bubshait <darkray@ic3man.com>, linux-kernel@vger.kernel.org
Subject: Re: AMD64 X2 lost ticks on PM timer
In-Reply-To: <20060227222152.GA26541@ti64.telemetry-investments.com>
Message-ID: <Pine.LNX.4.61.0602271744270.31386@dhcp83-105.boston.redhat.com>
References: <200602280022.40769.darkray@ic3man.com>
 <20060227222152.GA26541@ti64.telemetry-investments.com>
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On Mon, 27 Feb 2006, Bill Rugolsky Jr. wrote:

> On Tue, Feb 28, 2006 at 12:22:40AM +0300, bubshait wrote:
> > 	Losing some ticks... checking if CPU frequency changed.
> > 	warning: many lost ticks.
> > 	Your time source seems to be instable or some driver is hogging interupts
> > 	rip __do_softirq+0x47/0xd1
> > 
> > adding report_lost_ticks only prints repeating messages like
> > 
> > 	Lost 3 timer tick(s)! rip __do_softirq+0x47/0xd1
> 
> I'm seeing tons of these on a Tyan 2895 (Nvidia CKO4) running FC4 with
> kernel-2.6.15-1.1830 (2.6.15.2) SMP: 
> 
> time.c: Lost 1 timer tick(s)! rip default_idle+0x37/0x7a)
> time.c: Lost 2 timer tick(s)! rip __do_softirq+0x55/0xd4)
> 
> [I've seen the same thing with earlier FC 2.6.14 kernels.]
> 
> On our systems the __do_softirq messages are strongly correlated with
> sata_nv interrupts, especially during our nightly tripwire-like fs
> checksum job.  Unfortunately, the log messages are not very informative.
> I'm not sure what ever happened to the following patch,
> 
> http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.5/2.5.64/2.5.64-mm3/broken-out/report-lost-ticks.patch
> 
> but it was dropped.
> 
> Unfortunately, I need to spend tomorrow patching kernels in search of a
> fix or workaround, as I have to start using these boxes in production,
> and they need to keep time.
> 

passing 'nohpet' and/or 'nopmtimer' will force the use of a different 
timer...but this is certainly a workaround, if it helps...


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