Controlling task concurrency

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wzambotti

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Joined: 23 Feb 11
Posts: 1
Australia
Message 36985 - Posted: 23 Feb 2011, 8:42:33 UTC

I have a 4 CPU system, Win XP, BIONC 6.10.58, SETI@HOME.

What settings are required so that all processors work on just one task at a time.

At the moment if I set CPU use to 100% then it insists on starting 4 tasks, one task for each CPU. If I set to 50% then it starts 2 tasks but distributes the tasks over all 4 CPUS (still) which works out to 25% on each CPU.

Clearly this last setup implies a single task can be distributed over more than one CPU.

So what is the setting to get a single task to distribute of all 4 CPUS?

Or in other words how do I limit the task concurrency to one while not effecting CPU percentage?

Walter
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Profile Gundolf Jahn

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Joined: 20 Dec 07
Posts: 1069
Germany
Message 36986 - Posted: 23 Feb 2011, 10:02:20 UTC - in response to Message 36985.  

AFAIK, the only project that currently has multi-threaded applications is AQUA@home.

Gruß,
Gundolf
Computer sind nicht alles im Leben. (Kleiner Scherz)
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Firedrake

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Joined: 20 Mar 11
Posts: 1
United States
Message 37233 - Posted: 20 Mar 2011, 14:37:03 UTC

I seem to have the opposite problem. I recently built a 6 core AMD system with an ATI GPU. I have my setting set to use 50% of the CPU's( so 3) but instead it runs 3 tasks over all 6 cores. Did I miss something or is this reversed from what it should be doing?
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Pepo
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Joined: 3 Apr 06
Posts: 547
Slovakia
Message 37235 - Posted: 20 Mar 2011, 17:25:12 UTC - in response to Message 37233.  
Last modified: 20 Mar 2011, 17:26:30 UTC

I recently built a 6 core AMD system with an ATI GPU. I have my setting set to use 50% of the CPU's (so 3) but instead it runs 3 tasks over all 6 cores.

From what I read - everything's correct BOINC-side. 3 cores allowed - 3 tasks running.

If you mean the detail that you've expected (well, approximately) seeing 3 fully loaded and 3 completely idle cores, then it's up to the OS whether it keeps processes and threads using the same core, or spreads the load...

(Personally on Win7 and i3/i5 CPUs I observe single tasks mostly being kept on their cores, with WinXP and Core/Core2 CPUs rather spreading the load over available cores and keeping them similarly loaded. Maybe it's because newer CPUs can temporarily switch off power for unused cores, but on the older ones this was irrelevant.)

Peter
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Message boards : Questions and problems : Controlling task concurrency

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