keeping time

[Jeffrey F. Bloss]

Matthew Flaschen wrote:

> Michael R. Head wrote:
> > On Mon, 2007-03-19 at 18:07 -0600, Mikus Grinbergs wrote:
> >> I have an Ubuntu 6.10 system running 24/7 which gains more
> >> than two hours every week.
> >>
> >> For the purposes of this discussion, assume that the system
> >> has *no* external inputs -- only me at the console -- no
> >> network connection of any kind.
> >>
> >> What can I set_up / tweak so that the time being kept by
> >> the system is more accurate ?
> > 
> > NTP is the software you want.
> 
> He said he doesn't have a network connection (or want to use it).  At
> any rate, gaining two hours per week is a serious problem, and is most
> likely caused by hardware.  Michael, I'd guess you need to replace your
> BIOS battery.

Actually 2 hours a week isn't horrible. My shiny new laptop would be
off by about 7-10 minutes a day without being adjusted. Oddly enough my
PIII/550 "server" apparently only skews by 4-5 or so.

Left to their own devices computers are notoriously poor time keepers
for a number of reasons. Not the least of which being the fact that
time calculations on Intel-based machines can be "suspended" if
processing power is needed for some other purpose. There's also no real
incentive for hardware manufacturers to build precision timepieces in
the first place, and at least some financial incentive not to. Dallas
clock modules were expensive, and even they weren't what anyone could
consider highly accurate. 

The standard reference point last I knew is around 50 "clock ticks" in
every million or so. It's been an issue since the dawn of the PC era,
and it's actually getting worse. A $5 watch is quite literally more
accurate than a $2000 computer. If that weren't true we'd have little
use for NTP, and periodic updating usually done either hourly or
daily. ;)

-- 
     _?_      Outside of a dog, a book is a man's best friend.
    (o o)         Inside of a dog, it's too dark to read.
-oOO-(_)--OOo------------------------------[ Groucho Marx ]---
                    http://wrench.homelinux.net/~jeff/

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