runc exec: implement CPU affinity #4327
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This is to include - opencontainers/runtime-spec#1261 - opencontainers/runtime-spec#1253 Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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As per - opencontainers/runtime-spec#1253 - opencontainers/runtime-spec#1261 CPU affinity can be set in two ways: 1. When creating/starting a container, in config.json's Process.ExecCPUAffinity, which is when applied to all execs. 2. When running an exec, in process.json's CPUAffinity, which applied to a given exec and overrides the value from (1). Add some basic tests. Note that older kernels (RHEL8, Ubuntu 20.04) change CPU affinity of a process to that of a container's cgroup, as soon as it is moved to that cgroup, while newer kernels (Ubuntu 24.04, Fedora 41) don't do that. Because of the above, - it's impossible to really test initial CPU affinity without adding debug logging to libcontainer/nsenter; - for older kernels, there can be a brief moment when exec's affinity is different than either initial or final affinity being set; - exec's final CPU affinity, if not specified, can be different depending on the kernel, therefore we don't test it. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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Currently a draft until runtime-spec vNext is released.
As per
CPU affinity can be set in two ways:
Process.ExecCPUAffinity, which is when applied to all execs.
applied to a given exec and overrides the value from (1).
Add some basic tests.
Note that older kernels (RHEL8, Ubuntu 20.04) change CPU affinity of a
process to that of a container's cgroup, as soon as it is moved to that
cgroup, while newer kernels (Ubuntu 24.04, Fedora 41) don't do that.
Because of the above,
debug logging to libcontainer/nsenter;
is different than either initial or final affinity being set;
depending on the kernel, therefore we don't test it.
Fixes: #3922