Multiple WUs

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Patrick Derwael (Yahoo)

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Message 392 - Posted: 15 Sep 2005, 14:07:13 UTC

Hi people,
Just a quickie: I noticed Boinc runs 2 WU on Seti and 4 on ProteinPredictor.
This is no problem as such, I just wonder why...

Any idea ?
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Profile Jord
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Message 393 - Posted: 15 Sep 2005, 14:22:43 UTC

What kind of system do you have? Something with multiple physical CPUs all capable of running Hyper Threaded?

Boinc allows for Multiple physical and logical CPUs to run multiple units at the same time. If yours is just one CPU without HT capabilities, then you may want to say where you see this behavior? In Task Manager?

What is Boinc Manager saying on this in the Work tab? Are there 6 units running at the same time, or are some preempted (meaning paused)? If some are, do you have the setting "Leave applications in memory while preempted?" set to Yes in your General preferences?

If the answer to all that is Yes, then it's normal. They aren't running, just taking up space in your memory and virtual memory awaiting their turn to continue.

If the answer to all that is No, you may want to exit Boinc completely and/or reboot your computer before starting Boinc again.
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Patrick Derwael (Yahoo)

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Message 394 - Posted: 15 Sep 2005, 14:45:47 UTC

I'm running on a very classical single processor laptop.

There is only one WU running at a time, the others are "preempted" or "ready to run"

In my general options, I have set "Leave applications in memory while preempted?" to No.
Restarting Boinc and/or rebooting does not makes any difference.

Note that I do not consider this as a problem, it is just a matter of curiosity, because I cannot find one single reason for Boinc to behave so !
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Profile Jord
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Message 395 - Posted: 15 Sep 2005, 14:54:53 UTC - in response to Message 394.  

Other work units in the list are cached ones. Ready to run means exactly that, they are waiting their turn to start. Preempted means paused. They have run for a while (your time set at "Switch between applications every XX minutes"), and are waiting for their turn to continue.

To be able to store them in memory means that if a project isn't writing its data to disk every so many seconds or minutes (this is called checkpointing), it will continue the unit where it left off the last time, unless you exited Boinc or reset the computer. Else such a unit would start from 0% all the time.

Most projects out there checkpoint, so you can set the "leave in memory" to No. Yet as soon as you have saved the new settings to the web page, you have to go to that project in Boinc Manager and update it so Boinc on your computer also knows your new settings.

But it's not a problem. Preempted just means Paused. It's not running, it's not dabbling in Yoga, it's just waiting its turn to continue. ;)

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Paul D. Buck

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Message 409 - Posted: 16 Sep 2005, 15:16:28 UTC

Note that if you look in the process list, preempted work will show up as additional process IF you have "leave in memory" selected. This is NOT a problem, unless they start consuming CPU.

I have had on occassion, seen 4 work units runing on my dual G5, usually shutting down BOINC will suffice. However, I would just suggest that you do a reboot as that will kill these "thrashing" zombies.

BOINC does not, at least the last time I looked at the code, do a "for 1 to n processors, make them alive". So, what can happen is BOINC tells a process to "sleep" and it doesn't get the word for some reason and keeps running. Worse, stopping BOINC does not always work as BOINC does not seem to "know" about some of these child processes. Hence the reboot to kill them all "... god will know his own."
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Message boards : BOINC Manager : Multiple WUs

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