> I wondered for a while if docker could make a fake /proc/cpuinfo This exists: https://github.com/lxc/lxcfs https://github.com/lxc/lxcfs lxcfs is a FUSE file

> I wondered for a while if docker could make a fake /proc/cpuinfo This exists: https://github.com/lxc/lxcfs https://github.com/lxc/lxcfs lxcfs is a FUSE filesystem that mocks /proc by inferring cgroup values in a way that makes other applications and libraries work without having to care about whether it runs in a container (to the best of its ability - there are definitely caveats). One such example is that /proc/uptime should reflect the uptime of the container, not the host; additionally /proc/cpuinfo reflects the number of CPUs as a combination of cpu.max and cpuset.cpus (whichever the lower bound is). As others also mentioned, inferring the number of CPUs could also be done using the sched_getaffinity syscall - this doesn't depend on /proc/cpuinfo, so depending on the library you're using you might be in a pickle.