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Multiprocessor utilisation

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Brickhead
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Message 3172 - Posted: 6 Sep 2004, 19:02:14 UTC

One of my recently cpdn-boinced boxes sports 2 processors, but cpdn only generates 50% cpu load. Not due to processor affinity or single-threadedness it seems, because the load is somewhat divided between the two (although unevenly so) and never pushes any of them to 100% load. Boinc (running as a service) does not trigger more than one cpdn process at once, as it does with the single-threaded sah client.

Does anyone know the reason for this behaviour? Can it be remedied?

I haven\'t tried cpdn on the quad-cpu box yet, maybe that one would stop at 25%...

Cheers,
Brickhead (cpdn newbie, sah intermediate)
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Profile Thyme Lawn
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Message 3181 - Posted: 6 Sep 2004, 19:52:01 UTC
Last modified: 6 Sep 2004, 19:52:22 UTC

Hi Brickhead,

It's going to be due to your general preferences or available disk space or (if you're running more than one project on the system) your relative resource allocations.

Things to check:

1) your CPDN resource allocation is greater than 50. BOINC has been known to only download 1 model if it isn't.

2) you have at least 600MB of disk space that BOINC can use for each CPDN model. If you're running more than 1 project your relative resource allocations control what percentage of the disk space available to BOINC each project can use. This can be a problem when CPDN is given a low resource allocation because it uses lots more disk space than other BOINC projects.

<a href="http://www.teampicard.net"><img src="http://www.teampicard.net/templates/fisubice/images/phpbb2_logo.jpg"></a><a href="http://climateapps2.oucs.ox.ac.uk/cpdnboinc/team_display.php?teamid=3">Join us here</a>
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Profile Keck_Komputers
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Message 3182 - Posted: 6 Sep 2004, 19:52:58 UTC

There is a problem with the CPU scheduler. If there is only work available from one project and that project has less than 50% of the resource share it will only run one process. When your other project gets work then both CPUs will get to work. I do not know how it behaves with 4 CPUs.
<br>John Keck -- BOINCing since 2002/12/08 -- <a href="http://www.boinc.dk/index.php?page=user_statistics&amp;project=cpdn&amp;userid=191"><img border="0" height="80" src="http://191.cpdn.sig.boinc.dk?188"></a>
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Brickhead
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Message 3185 - Posted: 6 Sep 2004, 20:45:59 UTC

OK, I get it. The very reason I joined cpdn was to put some computers to work while waiting for available sah work. Thus, I'm not very eager to crank up the resource share beyond 50%. No biggie anyway, this will only affect two p3-500 and four Xeon-550 processors, certainly not the latest and greatest around.

Thanks guys:-)

BTW Thyme, is your team recruiting? If so, how much of a trekkie does one have to be to fit in?
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Message 3199 - Posted: 7 Sep 2004, 2:30:27 UTC - in response to Message 3185.  

&gt; OK, I get it. The very reason I joined cpdn was to put some computers to work
&gt; while waiting for available sah work. Thus, I'm not very eager to crank up the
&gt; resource share beyond 50%. No biggie anyway, this will only affect two p3-500
&gt; and four Xeon-550 processors, certainly not the latest and greatest around.
&gt;
&gt; Thanks guys:-)
&gt;
&gt; BTW Thyme, is your team recruiting? If so, how much of a trekkie does one have
&gt; to be to fit in?
&gt;

All are welcome, to join or just visit.
<a href="http://climateapps2.oucs.ox.ac.uk/cpdnboinc/team_display.php?teamid=3"><img src="http://www.teampicard.net/templates/fisubice/images/phpbb2_logo.jpg"></a>
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Message 3543 - Posted: 9 Sep 2004, 1:48:13 UTC - in response to Message 3172.  

&gt; One of my recently cpdn-boinced boxes sports 2 processors, but cpdn only
&gt; generates 50% cpu load. Not due to processor affinity or single-threadedness
&gt; it seems, because the load is somewhat divided between the two (although
&gt; unevenly so) and never pushes any of them to 100% load. Boinc (running as a
&gt; service) does not trigger more than one cpdn process at once, as it does with
&gt; the single-threaded sah client.
&gt;
&gt; Does anyone know the reason for this behaviour? Can it be remedied?
&gt;
&gt; I haven't tried cpdn on the quad-cpu box yet, maybe that one would stop at
&gt; 25%...
&gt;
&gt; Cheers,
&gt; Brickhead (cpdn newbie, sah intermediate)
&gt;
&gt;
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Message 3544 - Posted: 9 Sep 2004, 1:49:25 UTC - in response to Message 3172.  

I'm running CPDN and Seti both on a Hypterthreaded 3.2ghz P4 and I'm seeing both projects running (looks like 2 CPUs) and 100% CPU.

Marc
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Message boards : Number crunching : Multiprocessor utilisation

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