procs_running field in
/proc/stat include the current process which is querying procfs?
Yes, it does. The
/proc/stat pseudofile is generated in
fs/proc/stat.c in the Linux kernel, by calling
nr_running() function is defined in
kernel/sched/core.c, which simply sums over all per-cpu process counters. The current process is not treated in any special way here, so it is included in the count.
On the absolutely idle system should we expect value to be 0 or 1 ?
Since a process must be reading the pseudo-file for the kernel to generate the contents, and such a process is always counted by the
nr_running() kernel function, we should always expect it to be at least 1.