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Line 1: − = CPU capability problem =+ − Because CRIU allows to live migrate containers (see [[Live migration | Live_migration]] for details) it might happen that CPU a container has been ran on differ from the target CPU. For typical programs this might be not a problem but if a program get compiled with optimization which use a particular CPU feature (say AVX instruction and etc) the lack of the feature on a destination machine will lead to execution exception in a best case.+ − Thus there should be a way to test if destination machine is capable of running container being migrated.+ − == Save CPU capabilities into an image file ==+ − CRIU does not write CPU capabilities into an image by default in a sake of speed. Instead one have to run CRIU as+ + + + + − + + + + + + + − to produce ''cpuinfo'' image file which consists of bits representing the capabilities current CPU support.+
fix spelling
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 <code>cpuinfo</code> command.
== Saving CPU capabilities into an image file ==
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 ==
criu cpuinfo dump
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 ==
While by default CRIU does not save CPU capabilities in image file, one can pass <code>--cpu-cap</code> option to force CRIU to save and check CPU capabilities on dump and restore accordingly.
[[Category:API]]