Hi, Further to the last email I found the command to see what was happening with the time: watch -n1 'date ; cat /proc/interrupts' Oh - and it seems like one of the following 2 things has "cured" my missing seconds: 1.) adding noapic clock=pmtmr notsc to the boot command or 2.) using Nvidia's Nforce driver (nvnet) for the Nforce4's CK802(?) NIC, instead of forcedeth with the module settings optimization=1 (CPU load optimization) and the polling interval set to 1000 us (poll_interval_in_us=1000) I hate it when I come to threads like this, with a big long list of things that might possibly be helping cure the problem, but never getting to the bottom of it - and hence never properly understanding it :( Anyone want to take a step back and summarise the problem for the enlightenment of the non-understanding plebs out here (like me)! Cheers, Jon Jonathan Brooks wrote:
Andi Kleen wrote:
On Thursday 27 October 2005 22:12, Jonathan Brooks wrote:
Err, I think my machine was automatically detected as SMP, with the appropriate kernel installed (it's a dual core machine).
Then notsc should work if it's really needed.
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.
It would surprise me if notsc would fix that, but you can try.
Last thing - and apologies if someone has already mentioned this, but what is the definitive way to check whether a machine is losing ticks?
The kernel prints a message in the log. If you don't see it you don't have the problem.
-Andi
Hi Andi,
I recently saw a suggestion for running cat /proc/interrupts, or something like that to check on the timing of updates.
Periodically I do see many lost ticks with dmesg - hence starting this thread ;) I confess to knowing absolutely nothing about timing in Linux, so can't comment on whether these kernel parameters should affect the time reported by the OS, but it seems logical to me....?
Best wishes,
Jon.
-- Jonathan Brooks (Ph.D.) Research Fellow PaIN Group, Department of Human Anatomy & Genetics University of Oxford, South Parks Road, Oxford, OX1 3QX tel: 01865 282654 fax: 01865 282656