Andi Kleen wrote:
On Thursday 27 October 2005 21:42, Langsdorf, Mark wrote:
On Thursday 27 October 2005 19:42, Langsdorf, Mark wrote:
Unofficially, clock=pmtmr should at least reduce the amount of lost ticks. I doubt it will help on 64bit kernels, which don't have this option (ok placebos are sometimes known to help on computers too clock= only exists on 32bit. I'll defer to you, Andi, but 2.6.13.4 definitely has PM timer support for AMD64. Is there really no way to force a particular time source on AMD64?
64bit doesn't have the modular timer drivers of 32bit.
There is notsc and nohpet and nopmtimer to disable specific time sources.
But TSC use on UP is somewhat hardcoded and it doesn't use the decision path of the SMP version, so far it would always use TSC.
As a workaround for SUSE users it might work to manually install a SMP kernel though - during the installation unselect the kernel-default kernel and manually select kernel-smp in the package selection. Then notsc and the other options should work I think.
notsc might do the trick on 64bit though. However it will only work on multi processor systems. On uniprocessor there is currently no way to force another clock. Okay. Would a patch to change this be accepted?
Probably yes
-Andi
Hi All, Quite enjoying finding out just how screwed up my system is ;) Err, I think my machine was automatically detected as SMP, with the appropriate kernel installed (it's a dual core machine). Incidentally, do these problems only relate to X2 chips and dual Opterons? If so, won't they all get SMP kernels by default? So the only thing needed is the nostc adding to the boot command? The only reason I ask is that I amended the following to my boot command: noapic clock=pmtmr nostc, but I still find that the clock is running too fast - it probably gains 10 mins over the space of an hour. Last thing - and apologies if someone has already mentioned this, but what is the definitive way to check whether a machine is losing ticks? Best wishes, Jon. -- Jonathan Brooks (Ph.D.) Research Assistant. PaIN Group, Department of Human Anatomy & Genetics, University of Oxford, South Parks Road, Oxford, OX1 3QX tel: +44(0)1865-282654 fax: +44(0)1865-282656 web: http://www.fmrib.ox.ac.uk/~jon