Re: AMD64 X2 lost ticks on PM timer

Jason Baron
2006-02-27T22:38:44Z

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...