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Schduler pulls two WUs to achieve 33.33% of Intel HT?

Schduler pulls two WUs to achieve 33.33% of Intel HT?

Message boards : Number crunching : Schduler pulls two WUs to achieve 33.33% of Intel HT?
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old_user58853

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Message 12103 - Posted: 26 Apr 2005, 12:54:29 UTC

I've been running for a couple of months now and decided Climate and Protein are more likely to help mankind (and myself) in my lifetime, than SETI... so I reallocated my resources several weeks ago. Since then my CP WU reached about 90% complete and it downloaded a second WU... I have the window set to 2 days... nevermind that I still had about 100hrs to go on the first WU, and only 1/3rd of the resource allocation...

But why does CPU time get allocated to the second WU before the first has completed? I believe part of the answer is that there are points in time when the scheduler decides it should run both HT threads against CP at the same time. This doesn't seem to make much sense. Seems it should just run a single thread against that first WU for a longer period of time, until it is finished.
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Profile Thyme Lawn
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Message 12106 - Posted: 26 Apr 2005, 14:17:15 UTC

Hi Mark,

BOINC will treat a Windows HT computer as 2 independent processors if your general preferences are set to use anything more than 1 CPU on multi-processor systems.

I'd guess that the second WU was downloaded when your Predictor@Home was starved of work (completed it's last WU and the project had no WUs to download to you). When this happens BOINC will get (and run) work for other projects so it doesn't have a processor sitting idle.
"The ultimate test of a moral society is the kind of world that it leaves to its children." - Dietrich Bonhoeffer
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Message 12110 - Posted: 27 Apr 2005, 1:53:11 UTC - in response to Message 12106.  

Well... I'm not positive, but don't believe that was the case. At any rate, now that I'm well loaded with protein and SETI WUs, it seems it should spend my climate time on the nearly completed WU, and leave the other until I'm starved for other work to do.

Since the climate allocation is 33%, it should now be devoting one CPU to protein and alternating another between all three projects.
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Message 12112 - Posted: 27 Apr 2005, 9:42:44 UTC - in response to Message 12110.  

> Since the climate allocation is 33%, it should now be devoting one CPU to
> protein and alternating another between all three projects.

Actually, if you have three projects with each having an equal share you should see a rotation between all three projects on the two CPUs.

And, you are just as likely to see two WU of one project running at the same time as not. Of course on larger systems like my dual Xeon you see as many as three of one project rather than a more expected one of each.

This all has to do with the way that the Resource Allocation/Resource Debt calculations play out. This is also why you can see other real odd things like work being halted just seconds before the Result would be complete ...
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Message 12192 - Posted: 1 May 2005, 6:49:01 UTC

On my dual CPU PC, BOINC likes to change from one project to the other at regular intervals. It runs 2 work units of CPDN while S@H is paused and then swaps every hour.
I changed the resource share on CPDN to 500 (83.3%) because the WU are much longer than SETI. The projects switch every hour for part of the day. The extra share that CPDN asks is delivered as a longer period during the day without project switching.
I can suspend one work unit, which will start a work unit from the other project.

I suspect that a HT would prefer to run two work units of the same project. This is, if a HT CPU could run two project as two threads? Running two different projects might mean that the CPU cache could not store sufficient data/program and would result in slower performance.

Interesting to see if the new dual core with HT will run successfully on 4 work units!
<img border=\"0\" src=\"http://www.boincstats.com/signature/user_28893.gif\" />
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Message 12261 - Posted: 4 May 2005, 2:43:01 UTC

Well, I think I may have finally notice a key clue to the mystery... Looks like Climate has a new version out there. The WU is "only" about 60MB. So, what it had done was download two versions of code for the climate project (old WU was 4.10, new one came down with code updates for 4.12), and was trying to allocate some resource to each version.... (now if I could just figure why it hasn't cleaned up the old code version and old WU now that it has completed and reported...)

Now that I'm up to BOINC 4.25, I just suspended the new WU and let it finish out the older one. I like the features of 4.25, but which I had some of the graphics and color coding of my prior version (what was it? 4.17?)
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Les Bayliss
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Message 12263 - Posted: 4 May 2005, 3:49:58 UTC

Have you tried the Advanced Visualisation, 2nd from the bottom, on the menu to the left of here?

Les
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Message boards : Number crunching : Schduler pulls two WUs to achieve 33.33% of Intel HT?

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