Task memory quesiton

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Paul Schauble

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Joined: 29 Aug 05
Posts: 68
Message 80643 - Posted: 1 Sep 2017, 8:37:11 UTC

I'm not sure if I need to ask here or at LHC, but I actually think this is a BOINC problem.

I just fixed a setup problem with VirtualBox and started running the vbox64 tasks for LHC.

My machine has a Xeon E3-1245 v3 CPU, 16GB memory, and Windows 10 64 bit. The CPU has 8 cores (4 with hyperthreading) but I have limited BOINC to 6 as a concession to summer heat.

I immediately notice that I can only run 4 vbox tasks, not 6. Looking at the memory allocation for two of the running tasks, I see the following:

LHCb Simulation 1.02 (vbox64)

Task                        1           2

BOINC  (task properties)                    
  working set                2.33GB     2.33GB
Task Manager (all figures in K)
  Working Set (mem)          9784        6128
  Peak working set (mem)    65168       69864 
  Memory (private)           5460        3364
  Memory (shared)            4324        2892
  Commit Size               84380       83196


Well, if BOINC thinks the tasks require 2.33GB memory, then I guess I understand why only 4 can run. But I don't see how BOINC gets that number given what task manager is showing.

Can someone please explain what is happening here?

Thanks,
++PLS
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Juha
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Joined: 20 Nov 12
Posts: 801
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Message 80654 - Posted: 1 Sep 2017, 16:52:24 UTC - in response to Message 80643.  

VirtualBox allocates memory for VMs in such a manner that neither BOINC or Windows Task Manager sees how much memory it really uses. BOINC works around that by using the task's estimated memory usage as its actual memory usage. Sometimes the estimate is accurate, other times not so much.

You can verify the actual memory usage by opening VirtualBox Manager (Oracle VM VirtualBox) and checking the Base Memory figure of the running VM. For any already completed and reported task you can check the actual memory usage from stderr of the task. For Theory task the line is "Setting Memory Size for VM. (630MB)".

I don't have any LHCb tasks at hand but 2,3 GB per task sounds about right.
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Message boards : Questions and problems : Task memory quesiton

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