On Mon, 22 Aug 2005 07:40:15 +0100, david@djwhome.demon.co.uk (David
Woolley) wrote:

The previous answer covers two posts so I've tried to intersperse the
text appropriately.

In article <1tihg1hs19vv51ofh79ebivmngi5h672h1@4ax.com>,
Louis Holleman <louis@holleman.demon.nl> wrote:

On Sun, 21 Aug 2005 13:34:04 -0400, Roger
<Delete-Invallid.stuff.groups@tm.net> wrote:

I've found that running BOINC 4.45 causes the clocks on the three
machines running BOINC to run slow.  Shut BOINC down and the clocks

You haven't said that you are using Windows, but Windows has known

Yes

problems with time keeping.  It tends to lose clock interrupts when doing
disk I/O (Linux also has this problem, particularly on fast machines

That's true, but usually it isn't 5 minutes or more a day and I'd
expect the same kind of operation from the different machines with the
exception of the amount of I/O.  Both machines in here do have a lot
of  I/O which is one of the reasons this one is not running BOINC as
it bogs down with so much I/O.  Still, I'd expect the same kind of
performance form BOINC 4.19, 4.25, and 4.45 unless they have a big
difference as far as I/O.  Both are running 400 MHz FSB (200 X 2) as I
recall.

where newer kernels use 1ms, rather than 10ms ticks - but Linux has

These are all early OEM versions of  XP Pro (I purchased all 4 disks
in a pack) with SP-2 and lots of anti-spyware, virus checking (which
uses a lot of clock cycles and I/O).

configuration options that can help mitigate this).  This time loss will
happen for any application that makes many disk accesses, and has been
reported for backup utilities (several minutes lost during a backup run!).

That is one of the things done here across the network and we are
talking many gigabytes.  Typical backups are several hundred Gigs. The
computers back each other up with the one in the shop being used
primarily for storage so it gets stuff from all the others.  It now
has close to 1.2 terabytes on it counting two 250 Gig USB drives (on
different busses)

(Windows also isn't suitable for accurate timing because one can't
interpolate between clock ticks and because it has large scheduling
latencies that mean that timing on a loaded system jitters by about 20ms.)

At least I don't have any "critical" timing apps, but it can mess with
the data returns and confuse some apps which usually complain.

BOINC should not be run with administrator privileges, so it should not
have the ability to directly compromise the clock and the use of Windows
is a sufficient reason for time keeping problems.

They are running under the user accounts and not admin.

keep good time.  I did not have this problem with earlier versions of
BOINC.

I imagine it has started making more disk accesses.  Of course, a virus
is also likely to hit the disk hard.

The computers *check* clean, but that is no guarantee.

The messing with the clocks which I have tied directly to the use of
BOINC 4.45 can really mess with some of the apps.

Another thing that contributes to timing slips on Windows is running
multi-media applications, as they cause the clock frequency to change,
greatly increasing the chance of lost interrupts.  You shouldn't run

It's not quite an hour (I've been doing this post in bits and pieces)
and the computer has lost well over a minute running 4.25 with no
active WUs and the CPU showing on the order of 1% utilization.  There
are no other apps running except the normal background stuff such as
firewall, bot checkers, AddAware, and NAV.

time of day critical applications on Windows.  (I suppose its just
possible that BOINC enabled multi-media clocks not realising that
Windows can't cope with them.)

I wonder why they'd use them in the first place although they do keep
track of the CPU time per WU.

<snip>

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com