Rob van der Heij wrote:
On 10/11/06, John Summerfield <[EMAIL PROTECTED]> wrote:
If the underlying hardware clock keeps good time, does the Linux clock
actually drift?
On zSeries, the Linux system clock was supposed to be locked to the
TOD (apart from the corrections by ntpd). That's because the TOD is
used to measure time rather than count by interrupts (similar to the
instruction counter in Intel CPUs). There have been bugs that caused
Linux system clock to drop behind. I believe those were/are bugs.
I'm feeling a little slow; is the TOD set by the operator for each VM
guest? Or managed by VM? Or, (if you have one of these features) by the
underlying hardware?
If no VM, then what?
I can fully understand why one shouldn't trust the operators' reading of
the trusty Timex, but does one really need to set the hardware clock on
a modern mainframe more often than I do on my PC hardware?
Let's ignore DST as a separate issue.
Yes indeed. NTP is based on UTC which does not have time changes. The
glibc locale define when your local clock is yanked forward or
backward, and by how much. The way that works is real cute. These are
files created by my test that wrote a new file every second:
30 2004-10-31 02:59:58.000000000 +0200 file61.tmp
30 2004-10-31 02:59:59.000000000 +0200 file62.tmp
29 2004-10-31 02:00:00.000000000 +0100 file63.tmp
29 2004-10-31 02:00:01.000000000 +0100 file64.tmp
That could bugger up* the make.
* look to the British meanings.
--
Cheers
John
-- spambait
[EMAIL PROTECTED] [EMAIL PROTECTED]
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