Re: [ck] [PATCH] dynamic-tick patch modified for SMP

Srivatsa Vaddagiri
2005-08-16T13:20:30Z

On Tue, Aug 16, 2005 at 02:30:51AM +1000, Con Kolivas wrote:
> Time definitely was lost the longer the machine was running.

I think I found the reason for time drift. Basically cur_timer->mark_offset
doesnt expect to be called from non-timer interrupt handler. Hence it drops
one jiffy from the lost count. I fixed this in some "crude" fashion and time
has not drifted so far or is pretty much close to what it was in pre-smp
version. Will find a neat way to fix this and post a patch soon.

> You mean disable it at runtime or not compile it in at all? Disabling it at
> runtime caused what I described to you as PIT mode (long stalls etc).

I think I have recreated this on a machine here. Disabling
CONFIG_DYN_TICK_APIC at compile-time didnt seem to make any difference. Will
look at this problem next.

--

Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017