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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. − + − to produce ''cpuinfo'' image file which consists of the running CPU information and bits representing the supported capabilities.+ − + Line 21:
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rewording, fixes
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 involvingf 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 ==
== Saving 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
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
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 ==
== Testing CPU capabilities ==
To check if the capabilities saved in ''cpuinfo'' image file is match to the current CPU one should run
To check if the capabilities saved in ''cpuinfo'' image file are matching those of the current CPU, one should run:
criu cpuinfo check
criu cpuinfo check
== Checkpoint/Restore with CPU capabilities ==
== Checkpoint/Restore with CPU capabilities ==
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.
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]]
[[Category:API]]