Is it possible to tell which cpus are hyperthreads of the same core?

Solution 1:

This link describes how to match physical id, core id, and sibling count to identify which entries in /proc/cpuinfo are on the same core, but I can make no claims as to its accuracy. It also looks similar to this question.

Solution 2:

cat /sys/devices/system/cpu/cpu0/topology/thread_siblings_list

will print comma-separated list of sibling cores for a particular physical CPU/core. I used cpu0 (first core) as example.

The same information can be extracted from "core id" fields in /proc/cpuinfo (thanks user61849).