In article <10kklq412rep0c6@corp.supernews.com>,
gheston@hiwaay.net (Gary Heston) wrote:

mijikin wrote:

Pentium III running Mandrake 9.0. I did not have this problem with

Applications can make the system clock on a PC lose sync, if they
interfere with interrupts.

This is linux; unpriviledged applications, like S@H and BOINC,
cannot disable interrupts.

However, the normal reason for lost clock interrupts on Linux is the IDE
disk device driver.  This is a particular problem on some relatively
recent systems because a modification was made (I think by Red Hat -
but I think Mandrake is very close to Red Hat) to the kernel that causes
it to increase the clock interrupt rate on fast processors, and there
are widespread reports, on the comp.protocols.time.ntp newsgroup of
lost interrupts as a result.  If you look through the archives of that
group, you might be able to find methods to force the HZ value back to
the traditional value of 100.

I also seem to remember a mention of "atomic clock"; again this is linux and
all common linux distributions already come with the full version of the
reference implementation of the NTP protocol, which corrects clock frequency
a well as phase (this is also available for Windows NT family systems, 
including XP, but is not supplied - the supplied software on 2000 and XP
does not implement the full protocol and does not implement the simplified
protocol properly).  However, you will not get the full benefit of clock
synchronisation software on a machine that is losing interrupts - its 
designed to correct for variations in temperature affecting rate, not
for complete lost ticks.

It appears that either the client or BOINC has a problem. Not a
big one on dedicated crunchers, but it could be on systems also
used for production work.

Neither can have such a problem on Linux or Unix; it is an OS problem
if you are losing timer interrupts.  (Applications can make the problem
happen more often, of course.)

(Note that Windows 3 derivatives are particularly prone to losing 
interrupts during multimedia operations, as they increase the clock
interrupt rate during these.)