pyRAPL errors when hyperthreading/SMT is disabled

[willowec]

Hello,

I have encountered an issue where if hyperthreading is disabled on my machine, pyRAPL errors out in pyRAPL.setup(). The problem appears to be that on my version of Debian Linux, the topology/ directory does not exist for disabled SMT cores. With SMT disabled on my machine, cores 0-15 are enabled and cores 16-31 are disabled. As shown in the error message below, the error occurs when pyRAPL attempts to access the topology/physical_package_id file for core 16, which does not exist.

Traceback (most recent call last):
  File "/home/willow/characterizing-pytorch-power/src/gen_dataset.py", line 182, in <module>
    pyRAPL.setup()
    ~~~~~~~~~~~~^^
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/pyRAPL.py", line 39, in setup
    pyRAPL._sensor = Sensor(devices=devices, socket_ids=socket_ids)
                     ~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/sensor.py", line 59, in __init__
    self._device_api[device] = DeviceAPIFactory.create_device_api(device, socket_ids)
                               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/device_api.py", line 186, in create_device_api
    return PkgAPI(socket_ids)
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/device_api.py", line 137, in __init__
    DeviceAPI.__init__(self, socket_ids)
    ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/device_api.py", line 68, in __init__
    all_socket_id = get_socket_ids()
  File "/home/willow/characterizing-pytorch-power/src/.venv/lib/python3.13/site-packages/pyRAPL/device_api.py", line 50, in get_socket_ids
    api_file = open('/sys/devices/system/cpu/cpu' + str(cpu_id) + '/topology/physical_package_id')
FileNotFoundError: [Errno 2] No such file or directory: '/sys/devices/system/cpu/cpu16/topology/physical_package_id'

Here is the relevant output of lscpu:

$ lscpu
Architecture:             x86_64
  CPU op-mode(s):         32-bit, 64-bit
  Address sizes:          46 bits physical, 48 bits virtual
  Byte Order:             Little Endian
CPU(s):                   32
  On-line CPU(s) list:    0-15
  Off-line CPU(s) list:   16-31
Vendor ID:                GenuineIntel
  Model name:             Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz
    CPU family:           6
    Model:                79
    Thread(s) per core:   1
    Core(s) per socket:   8
    ...

And my system information:

$ uname -a
Linux broadwell-ep 6.12.25-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.25-1 (2025-04-25) x86_64 GNU/Linux

If you are open to community contributions, let me know and if I have the time I'm happy to whip up a PR.
Thanks,
Willow