In Linux lassen sich noch vor dem Start des Kernels bestimmte CPU-Kerne von der Nutzung ausschließen. Das kann unter anderem dann hilfreich sein, wenn es Probleme beim Start an defekten Geräten oder während der Ausführung der Tests gibt. Zu diesen Problemen können Abstürze und ähnliches gehören. Es ist jedoch wichtig zu wissen, dass auch das Testen von defekten CPU-Kernen grundsätzlich kein Problem darstellt. In seltenen Fällen können defekte CPU-Kerne jedoch zum Absturz des Geräts ganz unabhängig von toolstar®testLX führen.
Exclude specific CPU cores from the scheduler
You can leave certain CPU cores active but exclude them from the automatic scheduler. This reduces the load on the cores. However, it is not guaranteed that no program is actually running on these CPU cores. To exclude or reserve certain cores, you can add the isolcpus=x-xattach.
This reserves a range of CPUs and excludes them from the classic scheduler. For example, if you isolcpus=4-7, cores 5, 6, 7 and 8 are reserved and are not actively used by the classic scheduler. However, certain programs can still run directly on these cores.
Completely disabling CPU cores before boot
In order to completely deactivate a certain number of CPU cores before starting the Linux kernel and thus exclude them from being used by the operating system and all programs, you can set the maxcpus=X append to the parameters. For example, to keep only a single core active, you can maxcpus=1 to the existing parameters.
Wenn Sie diese Einstellung Nutzung können Sie in toolstar®testLX nicht alle CPU-Kerne verwenden und werden auch nur die Anzahl an Kernen in der Systemübersicht sehen, die wirklich vorhanden sind.
Completely disabling CPU cores after boot
To deactivate a core after starting the operating system, you can modify the individual cores in the Linux virtual file system under the sys/devices/system/cpu/ directory by entering a 0 in the respective online file. For example, if you want to disable core 2, you can write:
cd /sys/devices/system/cpu/cpu2
echo 0 > online
With this procedure, however, the core may have already been used when the operating system or one of the services started. In order to achieve complete deactivation/non-use, the cores must be deactivated before the kernel starts.
Enabling disabled CPU cores after boot
To activate a core after starting the operating system, you can modify the individual cores in the Linux virtual file system under the sys/devices/system/cpu/ directory by entering a 1 in the respective online file. For example, if you want to disable core 2, you can write:
cd /sys/devices/system/cpu/cpu2
echo 1 > online
