priority of tasks

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MathiasB

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Message 100274 - Posted: 11 Aug 2020, 5:44:16 UTC
Last modified: 11 Aug 2020, 6:06:05 UTC

Hi, just an idea/question.

Does BOINC weight tasks closer to the expiration date higher or if not,
would it make sense to do so in a special time frame?

And I see no difference in the remaining time when I switch between 25% CPU time and 75%...BOINC uses it, I see it in the task manager (W10) but why does the remaining time not change (???)

cheers & thx
Mathias
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robsmith
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Message 100275 - Posted: 11 Aug 2020, 6:46:56 UTC

BOINC normally runs in First-in, First-out mode. If it thinks a non-running task is not going to meet its deadline if it started on that schedule it is promoted to run ahead of schedule.

There are two different settings for CPU usage, "Use at most x% of the CPU cores" and "Use the CPU x% of the time" - let's dive into them (simple explanation):

The first means if you have a 4-core CPU, and have it set to 50% BOINC will use 2 of the cores. For most projects this will have no impact on the expected time it takes a task to complete, just how many tasks can be run concurrently.

The second causes BOINC to allow the applications to run in (very) short bursts, swapping in and out of use about 1 once per second (it may be faster). So, if we have this set to 50% in that 1 second period the application will run for half a second, and do nothing for the next half second. Obviously this will double the clock time to complete the task. But the estimated duration of a task may not change as that is based on CPU time (number of seconds where the task is actually being processed).
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MathiasB

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Message 100276 - Posted: 11 Aug 2020, 6:55:19 UTC - in response to Message 100275.  

thx!
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Mike Gibson

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Message 100279 - Posted: 11 Aug 2020, 15:03:16 UTC - in response to Message 100276.  

If we move on a stage. If you have units that are not completed within 3.5 days, your machine will not be considered as 'reliable' and so will not get re-sends which have only a 3.5 day deadline. If that is the case, then reduce the number of that project that you hold in cache in your Device Profiles.
Mike
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robsmith
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Message 100280 - Posted: 11 Aug 2020, 16:11:40 UTC - in response to Message 100279.  

Without knowing what project you, and the OP are talking about that is a very crude generalisation. For example CPDN tasks take anything from a day to several weeks to complete.
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Profile Dave
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Message 100281 - Posted: 11 Aug 2020, 16:15:06 UTC

The first means if you have a 4-core CPU, and have it set to 50% BOINC will use 2 of the cores. For most projects this will have no impact on the expected time it takes a task to complete, just how many tasks can be run concurrently.


The exception to this is if you have insufficient memory. CPDN is the only project I know much about this aspect but some of the current tasks peak at 1.4GB RAM usage/task. There have been some in testing that went up to 5GB/core. The 1.4GB of RAM ones are fine on my laptop from the point of view of RAM with 2GB/core but slow down with 4 because of lack of cache memory in the processor. The 5GB/task ones from testing slowed down marginally running two tasks and progressively more with three and four as more use was made of my swap partition. However overall throughput of these tasks still increased up the the maximum of using all four cores.
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Richard Haselgrove
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Message 100283 - Posted: 11 Aug 2020, 17:00:17 UTC - in response to Message 100279.  

If we move on a stage. If you have units that are not completed within 3.5 days, your machine will not be considered as 'reliable' and so will not get re-sends which have only a 3.5 day deadline. If that is the case, then reduce the number of that project that you hold in cache in your Device Profiles.
Mike
That precise statement is true for at least one project - Numberfields@Home. As others have said, other projects have widely different policies and practices.

When speaking of BOINC, you have to distinguish between BOINC generalities, and project specifics.
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Mike Gibson

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Message 100288 - Posted: 12 Aug 2020, 0:21:36 UTC - in response to Message 100283.  

Sorry, I was referring to WCG where the deadline is 7 days regardless of how long the units take. Then any re-sends after 3.5 days get 3.5 days regardless.

Mike
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Message boards : Questions and problems : priority of tasks

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