Difference between revisions of "Processes in D state"
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If there are a lot of processes in D state in your system, then something is wrong with it. | If there are a lot of processes in D state in your system, then something is wrong with it. | ||
| − | What is | + | |
| − | sleeping | + | What is '''D state''' and a process state in general? A process in Linux can be in several states: running, |
| − | or for some other event. Using ps command you can obtain information about state of each process in the system: STAT column shows that: | + | sleeping, etc. Running process runs on a CPU just now, sleeping process waits for its turn on CPU |
| + | or for some other event. Using <tt>ps</tt> command you can obtain information about state of each process in the system: STAT column shows that: | ||
<pre> | <pre> | ||
| − | + | # ps a | |
PID TTY STAT TIME COMMAND | PID TTY STAT TIME COMMAND | ||
4975 tty1 Ss+ 0:00 /sbin/mingetty tty1 | 4975 tty1 Ss+ 0:00 /sbin/mingetty tty1 | ||
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</pre> | </pre> | ||
| − | First big '''S''' stands for Sleeping, '''R''' stands for | + | First big '''S''' stands for Sleeping, '''R''' stands for running ("+" means that the process is foreground and small "s" means that the process is session leader, but it is not relevant for this article). |
| − | ("+" means that the process is foreground and small "s" means that the process is session leader, but it | + | |
| − | D state occurs then the process is in | + | '''D''' state occurs then the process is in uninterruptible disk sleep. This state is bad, because you can't do anything with the process in D state. Fortunately, process normally remains in such state not for so long. But if you have a heap of D state processes then some logic in system is disrupt. If that is happening, the very important thing is to determine where this unlucky sleep occurs. It is easy to do with ps command with ''l'' option. WCHAN column shows the name of the kernel function where the process is sleeping: |
| − | Fortunately, process normally remains in such state not for long. | ||
| − | |||
| − | where this unlucky sleep occurs. It is easy to do with ps command with ''l'' option. WCHAN column shows the name of the kernel function where | ||
| − | the process is sleeping: | ||
<pre> | <pre> | ||
| − | + | # ps axl | grep D | |
F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND | F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND | ||
vass 13478 7.2 0.0 1732 624 pts/1 D+ 17:36 0:00 find ./ | vass 13478 7.2 0.0 1732 624 pts/1 D+ 17:36 0:00 find ./ | ||
</pre> | </pre> | ||
| − | + | {{Note|In case you have problem with the D state processes, always attach this information to the report you send to developers.}} | |
[[Category: Troubleshooting]] | [[Category: Troubleshooting]] | ||
Revision as of 21:10, 12 June 2006
If there are a lot of processes in D state in your system, then something is wrong with it.
What is D state and a process state in general? A process in Linux can be in several states: running, sleeping, etc. Running process runs on a CPU just now, sleeping process waits for its turn on CPU or for some other event. Using ps command you can obtain information about state of each process in the system: STAT column shows that:
# ps a PID TTY STAT TIME COMMAND 4975 tty1 Ss+ 0:00 /sbin/mingetty tty1 4976 tty2 Ss+ 0:00 /sbin/mingetty tty2 6202 pts/0 Ss+ 0:01 -bash 10312 pts/1 Ss 0:00 -bash 639 pts/1 R+ 0:00 ps a
First big S stands for Sleeping, R stands for running ("+" means that the process is foreground and small "s" means that the process is session leader, but it is not relevant for this article).
D state occurs then the process is in uninterruptible disk sleep. This state is bad, because you can't do anything with the process in D state. Fortunately, process normally remains in such state not for so long. But if you have a heap of D state processes then some logic in system is disrupt. If that is happening, the very important thing is to determine where this unlucky sleep occurs. It is easy to do with ps command with l option. WCHAN column shows the name of the kernel function where the process is sleeping:
# ps axl | grep D F UID PID PPID PRI NI VSZ RSS WCHAN STAT TTY TIME COMMAND vass 13478 7.2 0.0 1732 624 pts/1 D+ 17:36 0:00 find ./
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Note: In case you have problem with the D state processes, always attach this information to the report you send to developers. |
