Re: AMD64 X2 lost ticks on PM timer

Bill Rugolsky Jr.
2006-02-27T22:21:59Z

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.

Regards,

Bill Rugolsky