Proposal optimizing the task scheduler

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schildbuerger

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Joined: 25 Nov 14
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Message 58185 - Posted: 25 Nov 2014, 23:43:15 UTC

Hello together,

in the current version of BOINC Manager the task scheduler starts all tasks at the same time and stops them, if configured to use less then 100% processor time, at the same time. If configured to use 25% processor time on a multi processor system, this behavior leads to a peek of 100% of processor capacity utilization followed by a period of idle utilization.

One of my computers works as a video disk recorder. This computer shows dropouts in its main job if it uses both cores for boinc tasks, and I need to restrict BOINC Manager to use only one of the two cores to avoid those dropouts. Even if I restrict the processor utilization to 60% or less there are dropouts in video displaying, so this computer can maximal spend 50% (= one core at 100%) prozessor time to compute boinc tasks without dropouts in its main job.

I see a very good chance to get better boinc performance, not only in my use case, if BOINC Manager starts the tasks asynchronous, eg. in a two core system first one task for the first scheduled period and after that the next task for the next schedule by a reduced process priority. In that case other processes with higher priority may get more computing time if needed and boinc tasks can be configured to use all cores with a high percentage of used processing time. In my expectance a typical win - win situation.

What does the communty says to my idea? Is there a chance that such an idea will be implemented if it is working?

Regards,
Klaus
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ChristianB
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Message 58204 - Posted: 26 Nov 2014, 8:38:09 UTC

Please specify the BOINC version you are useing. The 7.4.x versions should have a feature called sub-second throttle. This should give the operating system scheduler more room to fullfill all needs of the system.

From a technical perspective the deferred start wouldn't help your particular problem, which may mainly be I/O related. Meaning that the recorder software is writing to disk almost constantly and thus needs one core permanently to write data as quick as possible. The usage may not be high but that's not what it needs, it needs latency. Which you don't have if the OS iss permanently switching between different processes.
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Juha
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Message 58225 - Posted: 26 Nov 2014, 19:26:06 UTC - in response to Message 58204.  
Last modified: 26 Nov 2014, 19:33:39 UTC

The 7.4.x versions should have a feature called sub-second throttle.

The sub-second throttling was withdrawn.

Client: don't use sub-second CPU throttling

I forgot that the wrapper has a 1-second poll for suspend and resume,
so sub-second throttling won't work properly for wrapper apps.
Revert to a variant of the old scheme,
in which the min of the suspended and resumed periods is 1 sec.

Also, fix task start/suspend/resume log messages.


It also didn't work for (really) old science apps and I think some people weren't happy how it worked for GPU apps.

edit: For Windows boxes there's TThrottle which does something similar but doesn't require support from BOINC or science apps.
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schildbuerger

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Message 58227 - Posted: 26 Nov 2014, 19:49:13 UTC - in response to Message 58204.  

Hello ChristianB,

thanks for your reply.

BOINC runs on a Ubuntu system. boinccmd -V shows 7.0.27.

I think, I have to update BOINC, but I'm out of office the next days so it will take some time, before I can do the job.

There is no X-Client running on the Ubuntu system, how do I update BOINC from command line?
I fond the following thread http://boinc.berkeley.edu/dev/forum_thread.php?id=5876#33815 with an update advisory from 2011. Is it up to date?

Regards,
Klaus
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schildbuerger

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Message 58228 - Posted: 26 Nov 2014, 19:57:27 UTC - in response to Message 58225.  

Hello JuHa,

the affecting machine is an Ubuntu 12.04.5 system which runs VDR as video recorder.

My BOINC software is outdated, and I think it's best to update it to the current BOINC version before taking further actions.

Thanks and Regards,
Klaus
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Juha
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Message 58230 - Posted: 26 Nov 2014, 21:26:20 UTC - in response to Message 58228.  

There's newer version in LocutusOfBorg's PPA. Follow the instructions in "Read about installing".
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schildbuerger

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Message 58776 - Posted: 20 Dec 2014, 19:58:59 UTC - in response to Message 58230.  

@Juha: Done. Thanks for your hint!
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Message boards : BOINC client : Proposal optimizing the task scheduler

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