Multithreadding not using all cores
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Partygott
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Message 11398 - Posted: 28 Jan 2026, 16:16:32 UTC

Hello.

I generated an app_config.xml to use more than one core per WU.
The file looks like this:

<app_config>
<app>
<name>srbase</name>
<fraction_done_exact/>
<max_concurrent>3</max_concurrent>
</app>
<app_version>
<app_name>srbase</app_name>
<cmdline>-t4</cmdline>
<avg_ncpus>4</avg_ncpus>
</app_version>
</app_config>

It is an i7-1355U with 10 cores and 12 threads.
BOINC is running 3 WUs with (4 CPUs) label but the task manager shows only 6-10% load per WU, so only about one core is used, while the idle task has about 60-75%.

I wanted to config the xml so that average use 4 and long WUs use all 12 possible threads but the cpu is only on full load when I take one core and 12 WUs.

So whats wrong about my config?
Thank you in advance.

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Message 11399 - Posted: 28 Jan 2026, 17:38:08 UTC

Try to change

<max_concurrent>3</max_concurrent>

to
<max_concurrent>1</max_concurrent>

Partygott
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Message 11402 - Posted: 29 Jan 2026, 8:42:38 UTC - in response to Message 11399.

I tried to change to

<max_concurrent>1</max_concurrent>
<cmdline>-t12</cmdline>
<avg_ncpus>12</avg_ncpus>

but then I have one WU running using only one core while boinc shows (12 CPUs)

I also tried to reset the project but no change.

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Message 11403 - Posted: 29 Jan 2026, 9:21:54 UTC
Last modified: 29 Jan 2026, 9:31:27 UTC

I see, you want 4x3 not 1x12. Do you have enabled HT in BIOS? MT should use 95% CPU usage.

Use this

<max_concurrent>3</max_concurrent> <cmdline>-t3</cmdline> <avg_ncpus>3</avg_ncpus>


or better 5, 2, 2 for 10 real cores

Partygott
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Message 11404 - Posted: 29 Jan 2026, 12:52:22 UTC - in response to Message 11403.
Last modified: 29 Jan 2026, 13:24:37 UTC

HT is turned on in BIOS and i cannot change this, cause it is a very minimalistic Lenovo ThinkPad BIOS.

I tried

<max_concurrent>2</max_concurrent>
<cmdline>-t5</cmdline>
<avg_ncpus>5</avg_ncpus>

and

<max_concurrent>3</max_concurrent>
<cmdline>-t3</cmdline>
<avg_ncpus>3</avg_ncpus>

and

<max_concurrent>4</max_concurrent>
<cmdline>-t3</cmdline>
<avg_ncpus>3</avg_ncpus>

and

<max_concurrent>1</max_concurrent>
<cmdline>-t12</cmdline>
<avg_ncpus>12</avg_ncpus>


With 1 or 2 cores per WU the load per WU is about 8% or respective 16%, while 8,33% per task is a 100% usage (100% / 12 threads = 8,33%).
But if I raise the amount of cores per WU the usage goes down, like 3-6% per WU at 5 cores. At 12 Cores per 1 WU, the usage drops to 1-3%.

I tested on another system with a 5800X CPU (Win10) and 2x 8 cores on 2 WUs brings about 90-99% usage, so it is not a question of correct app_config settings.

I also tried another project (Amicable Numbers) and a 12 Core WU reaches about 80-85% usage.
But here the app itself uses all cores per WU without needing an app_config file.

So it seems to be a problem with Win11, strange configs by company policies or something else in BOINC or the srbase exe.

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Message 11406 - Posted: 29 Jan 2026, 13:53:45 UTC

Perhaps something with powerplan or overheat of the GPU itself which reduce the speed. I'am not recommened to run anything heavy load on laptops.


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