htop 3.2.2 running as a regular user only shows I/O rates (IO_RATE/IO_READ_RATE/IO_WRITE_RATE) for some processes and "N/A" for others.
Running as root shows I/O for all processes.
How can I configure htop show I/O rates for all processes while running as a regular user?
htop tries to read the /proc/pid/io file for each process to get I/O statistics.
Near the end of the /proc/pid/io section of proc(5) we have:
Permission to access this file is governed by a ptrace access mode
PTRACE_MODE_READ_FSCREDScheck; see ptrace(2).
General ptrace() permissions can be granted with CAP_SYS_PTRACE but we also need CAP_DAC_READ_SEARCH to bypass the file-read permission checks done by the ptrace() access algorithm.
setcap(8) can be used to set both capabilities on the htop executable:
sudo setcap 'cap_sys_ptrace=ep cap_dac_read_search=ep' /usr/bin/htop The cap bits can be verified with:
sudo getcap /usr/bin/htop ...or reset all together:
sudo setcap '' /usr/bin/htop