isolcpus kernel parameter is ignored - make use of one STM32MP257 core only?

HMüll.4 · ‎2025-03-25

Hi,

I'm trying to run the whole ST-Linux-stuff on one core only to have the other one available for a time-consuming application. However, it seems the kernel-parameter isolcpus is not used, dmesg gives an output

[    0.000000] Kernel command line: root=PARTUUID=e91c4e10-16e6-4c0e-bd0e-77becf4a3582 rootwait rw   earlycon console=ttySTM0,115200 isolcpus=0
[    0.000000] Unknown kernel command line parameters "isolcpus=0", will be passed to user space.
[    2.309368]     isolcpus=0

The message is correct, also with this parameter set, the processes are spread over all cores.

What could be the problem here?

Thanks!

Erwan SZYMANSKI · ‎2025-03-28

Hello @HMüll.4 ,
I find it strange that you have this warning on your second line. I have it too using the same command line parameter as you have. However, using 1 as parameter, the warning is not here anymore and it seems to have the expected result.
Can you please make a try with isolcpus=1 instead of 0 ?

Kind regards,
Erwan.

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Erwan SZYMANSKI · ‎2025-03-28

Hello @HMüll.4 ,
I find it strange that you have this warning on your second line. I have it too using the same command line parameter as you have. However, using 1 as parameter, the warning is not here anymore and it seems to have the expected result.
Can you please make a try with isolcpus=1 instead of 0 ?

Kind regards,
Erwan.

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.