LHC@home

I have an i5-3570K, 32GB RAM, and at the moment two LHC tasks are running, along with a Xansons task on the AMD Radeon R9 290. The computer is extremely sluggish, sometimes it takes a few seconds to just open the start menu. CPU usage is between 60 and 80% in the task manager. What's the best way (if there is one) to prevent this happening? It only occurs with LHC on the processor, so I assume it's to do with Virtualbox.

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Hi, Peter,
It shouldn't be that slow with only 60-80% CPU usage. My 3 hosts run constantly at close to 100% with little noticeable drop in performance.
There are a few OPTIONS in Boinc Manager. You could set to only use 3 of you 4 logical cores, 75%, to leave 1 core free for other purposes or tick the "Suspend while computer is in use" box or "Suspend when non-Boinc CPU usage is above" say 50% or whatever you fancy.

I'm only using TWO of the 4 cores for LHC tasks. I always do that, so I have one free for me, and one free to assist GPU tasks. I used to run three CPU tasks, but sometimes the GPU task would end up getting throttled waiting for the CPU assist.

I don't want to suspend the tasks while in use, I'd rather it was getting on with things. Before LHC, the only thing I had to suspend was GPU tasks while a game was playing.

I was wondering if perhaps Virtualbox could be tuned in some way? It appears to be acting like the CPU is overworked, but I can see that it isn't. So perhaps it's taking too long between task-switching? Back in the days of Windows 3, you could change the number of ms per task before it changed to the next.

BOINC has just switched to doing one Einstein and one LHC on the CPU cores. It's now running smoothly. So it's only when there are two LHCs running. Perhaps two virtualboxes at once is causing a problem and I need to adjust something? Maybe my CPU isn't capable of using virtualisation technology twice at once?

Actually, it's behaving as though the machine is out of memory and it's swapping to disk (which it isn't) - you know when it's disk swapping and opening an application you can actually see it drawing individual parts on the screen?

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Hi Peter,

It's surely caused by VirtualBox. Their processes normally are running with the same priority as the user. Priority = 'Normal'.
That's against BOINC's principle to run at lowest priority, but several versions ago Oracle decided that the process priority
of VBox-processes can't be changed when already running.

One solution is before starting BOINC VBox tasks, open VirtualBox Manager, go to Task Manager and lower the process priority of the VBoxSVC.exe process to 'below normal'.
Then you can start BOINC's VBox processes and the VBoxHeadless.exe's will also get the 'below normal' priority.
There are tools to automate this.

That didn't seem to help. And my CPU is not maxed out anyway.

Task manager shows all the headless.exes got below normal as you said they would, but the interface is still sluggish.

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are you sure that this is not caused by your GPU?
because when i use my GPU for crunching and not suspending work while the computer is in use, it gets really sluggish as well. after suspending gpu work the pc runs smoothly, even with active vbox crunching.

Definitely the vbox. I just tried running only 2 vbox LHC tasks (on a quad core processor), and double clicking a jpeg to open it in paintshop took 3 or 4 seconds. I then ran only xansons on the gpu, and they opened instantly.

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Peter Hucker wrote:

... they opened instantly.

Did you restart the computer before the second test?
If not, paintshop as well as the jpeg were most likely taken from the disk cache.

The disk cache seems irrelevant. I can reopen the same jpeg again and again and it's slow every time if two LHCs are running.

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On my PC, I use the "do not run when user is active" setting to avoid this. BOINC should pause VirtualBox and memory consumption come down.

I don't want to do that. I've got 4 CPU cores and I certainly don't need them all to myself. The computer could be doing something useful at the same time (ie. BOINC). And usually even if I do need most of the cores, BOINC runs at low priority and gets out of the way by slowing down temporarily. I haven't had this problem with any project apart from LHC.

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