LHC@home

Intel i7-4790K (8 logical cores)
Prefs set to use 75% (6 cores)
OpenSuSE Tumbleweed, Kernel 6.17.5-1-default
BOINC 8.2.2

Hello,
Is anybody else getting odd scheduling?
4 cores (~400%) for ATLAS is OK. But 2 cores (~200%) for a Theory?
I've looked at the Event log with cpu_sched_debug enabled and there's no sign of any panic.
Theory jobs are not supposed to be multi-thread (mt), but:

~> top

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND

   9352 boinc     30  10 4869716 3.272g 3.241g S 411.7 10.54 296:22.36 VBoxHeadless        ; ATLAS  (vbox64_mt_mcore_atlas)
   9936 boinc     30  10 3390776 2.040g 2.027g S 192.1 6.569  38:41.71 VBoxHeadless        ; Theory (vbox64_theory)
   5999 boinc     30  10 4170032 2.725g 2.704g S 186.8 8.777 300:06.29 VBoxHeadless        ; Theory (vbox64_theory)

So that's all 8 cores used. (The slight shortfall in CPU total use is because there is another project running a GPU app with a fractional CPU assigned to it.)

This is the BOINC Manager Event log with cpu_sched_status enabled:

Thu 30 Oct 2025 14:29:16 GMT | LHC@home | [css] running Theory_2922-4824845-349_1 ( )
Thu 30 Oct 2025 14:29:16 GMT | LHC@home | [css] running Theory_2922-4879164-356_0 ( )
Thu 30 Oct 2025 14:29:16 GMT | LHC@home | [css] running 4xAMDmrpEY8n9Rq4apOajLDm4fhM0noT9bVof3QYDm2LoMDmOZrbHn_0 (4 CPUs)

BOINC may be overriding my settings to get the jobs finished in time, but there's no sign of that in the Event log. And specifically the ~2 cores used by Theory is very odd.
Any insights?
Thanks.

This is a bug in VirtualBox 7.2.4.

On a computer with AMD CPU there's no known workaround so far.
On a computer with Intel CPU you may try to
- install VirtualBox 7.2.2 (all distro version) from the VirtualBox site
- disable the kvm blacklisting suggested to work around earlier VirtualBox bugs

There are a couple of posts mentioning this at the VirtualBox forum.

Thank you computezrmle. I will look into it...

Curiously - as if further evidence of strangeness were needed, one of the ~200% Theory tasks has just completed. Here's the listing from my LHC@home Tasks web page

Task          Work unit     Computer    Sent                        Time reported                Status                       Run time(sec)    CPU time(sec)    Credit    Application

430147198     237250672     10860321    30 Oct 2025, 0:01:57 UTC    30 Oct 2025, 15:34:55 UTC    Completed and validated      55,978.00        77,546.53        845.81    Theory Simulation v301.00 (vbox64_theory)
                                                                                                                                                                          x86_64-pc-linux-gnu

It may be useful to observe that other Theory tasks had Run time and CPU time about the same.

The new Theory task that replaced this behaved properly and ran on just one core - initially. Now it's on 2 cores.
And now the ATLAS is on 2 cores only - as are both the Theories... That's the 75% of my CPU I'm aiming for in the settings. Fun. Well I've got a lead now. That VirtualBox is a hoot.
Thanks again!

Yes thank you. VirtualBox 7.2.2 works correctly.

~> top

PID   USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND

17148 boinc     39  19 5408132 3.791g 3.771g S 394.7 12.21   2:00.66 VBoxHeadless
17317 boinc     39  19 3393476 2.053g 2.040g S 99.00 6.611   0:22.36 VBoxHeadless
17156 boinc     39  19 3434600 2.092g 2.079g S 98.67 6.737   0:42.92 VBoxHeadless

And I didn't disable any kvm blacklisting...

Thank you!
Wishing all a Happy Halloween tomorrow

This is a bug in VirtualBox 7.2.4.

On a computer with AMD CPU there's no known workaround so far.
...

After more testing...
Looks like the downgrade left the 7.2.4 kernel module on the system.
It now works after a cleanup and a fresh 7.2.2 installation (package from VirtualBox).

The kvm_amd module must remain blacklisted.