compaq nx9000 & fedora core 2/3test3 - clock slow

[David Timms]

I have noticed since upgrading to fedora core 2, and also core 3test that the system clock on the laptop runs slow.

The clock ran normally under FC1. Under the latest two versions, the desktop clock (2.8.1), is set to internet time on machine bootup, but then quickly loses time. Today, with wireless network access running it is taking 70seconds to pass a real minute. But generally it's even slower than this: 75 - 90 seconds to pass one minute.

Re-setting system time using the ntp source fixes it, but it soon drifts away from the real time. Under winXP clock is OK.

I understand that the OS retrieves the RTC time at boot, and then free runs based on a timing loop, before writing the time back to RTC at os shutdown ?

So it seems the calibration of the delay loop is out of whack (both the kernels are 2.6 series). Where can it be fixed ?

[an interesting side effect is that I get apparent broadband download speeds 90/60 % better than my real connection speed ;-) ]

[Bruce Copeland · Accepted solution]

I noticed similar problems after upgrading my HP ze4100 notebook to FC2. I was able to resolve the problem by adding the parameter

clock=pmtmr

to my kernel boot line. The kernel can use one of several different clock sources. On this hardware, pmtmr seems to be much more reliable than the default used in 2.6 kernels.

Bruce

[David Timms]

Bruce, will give this a try when my downloads finish...

[David Timms]

As Bruce suggested, in file:
/boot/grub/grub.conf, for my fedora boot entry, add
clock=pmtmr
to the kernel line.
My clock now runs to within 0.25 second over a minute, which is probably good enough without seeing eg how long it loses in a day.

Thanks Bruce.