(Redirected from CLI/opt/--cpu-cap)
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Because CRIU allows to live migrate containers (see live migration for details), it might happen that CPU a container has been ran on differs from the target CPU. For most software this is usually not a problem, but if a program is compiled with optimizations involving a particular CPU feature (say, AVX instruction), the lack of the feature on a destination machine will lead to execution exception in a best case scenario.

Therefore there should be a way to test if destination machine is capable of running container to be migrated. This is the purpose of cpuinfo command.

Saving CPU capabilities into an image file[edit]

CRIU does not write CPU capabilities into an image by default (for the sake of speed). Instead, one have to run CRIU as:

 criu cpuinfo dump

The command creates a cpuinfo image file, containing information about the current CPU and some bits representing the supported capabilities.

Testing CPU capabilities[edit]

To check if the capabilities saved in cpuinfo image file are matching those of the current CPU, one should run:

 criu cpuinfo check

Checkpoint/Restore with CPU capabilities[edit]

While by default CRIU does not save CPU capabilities in image file, one can pass --cpu-cap option to force CRIU to save and check CPU capabilities on dump and restore accordingly.