Difference between revisions of "Cpuinfo"
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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 <code>cpuinfo</code> command. | |
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== 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 | + | 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 | + | 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 | ||
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== 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 | + | 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. |
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| + | [[Category:API]] | ||
Latest revision as of 08:17, 9 January 2018
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.