What is the meaning of
R / D from
ps ax? Does it indicate a problem?
3 ? R 522:45 [ksoftirqd/0] 4380 ? Rl 1240:31 gdm-session-worker [pam/gdm-launch-environment] 5938 ? Rs 0:00 ps ax 6148 ? Rl 1405:54 gnome-shell --mode=gdm
ps manual, under the section "PROCESS STATE CODES":
D uninterruptible sleep (usually IO) R running or runnable (on run queue) S interruptible sleep (waiting for an event to complete) T stopped by job control signal t stopped by debugger during the tracing W paging (not valid since the 2.6.xx kernel) X dead (should never be seen) Z defunct ("zombie") process, terminated but not reaped by its parent
R means that the process is in the run queue. It does not in any way indicate a problem.
A process in a
D state will not handle signals straight away as it's currently stuck waiting for disk (usually, and this is where the letter D in the code comes from). This would indicate an issue if the process is stuck for a longer period of time or if multiple processes are in the same state. The problem is then probably related to high I/O load (too many processes wanting to read from a too slow disk, for example).
The additional character is also explained:
For BSD formats and when the stat keyword is used, additional characters may be displayed:
< high-priority (not nice to other users) N low-priority (nice to other users) L has pages locked into memory (for real-time and custom IO) s is a session leader l is multi-threaded (using CLONE_THREAD, like NPTL pthreads do) + is in the foreground process group