Improve the message that is printed when Linux taskstats are not found
Usually this means that iotop is being run in a container.
The Linux kernel doesn't support taskstats outside the host net namespace.
There was a patch that looks like it may fix this but it never got merged.
Traceback (most recent call last):
File "/usr/sbin/iotop", line 17, in <module>
main()
File "/usr/lib/python3/dist-packages/iotop/ui.py", line 737, in main
main_loop()
File "/usr/lib/python3/dist-packages/iotop/ui.py", line 727, in <lambda>
main_loop = lambda: run_iotop(options)
File "/usr/lib/python3/dist-packages/iotop/ui.py", line 618, in run_iotop
return run_iotop_window(None, options)
File "/usr/lib/python3/dist-packages/iotop/ui.py", line 609, in run_iotop_window
taskstats_connection = TaskStatsNetlink(options)
File "/usr/lib/python3/dist-packages/iotop/data.py", line 151, in __init__
self.family_id = controller.get_family_id('TASKSTATS')
File "/usr/lib/python3/dist-packages/iotop/genetlink.py", line 76, in get_family_id
m = GeNlMessage.recv(self.conn)
File "/usr/lib/python3/dist-packages/iotop/genetlink.py", line 56, in recv
msg = conn.recv()
File "/usr/lib/python3/dist-packages/iotop/netlink.py", line 255, in recv
raise err
OSError: Netlink error: No such file or directory (2)
See-also: https://blog.outlyer.com/using-netlink-to-calculate-load-averages
See-also: https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg924689.html
See-also: https://bugzilla.redhat.com/show_bug.cgi?id=
1290691
See-also: https://bugs.openvz.org/browse/OVZ-5655