Editing 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 "D state" and process state in generally? A process in Linux can be in several states: runing state, | |
| − | What is | + | sleeping state and others. Running process runs on a CPU just now, Sleeping process waits for its turn on CPU |
| − | sleeping | + | or for some other event. Using ps command you can obtain information about state of each process in the system: STAT column shows that: |
| − | or for some other event. Using | ||
<pre> | <pre> | ||
| − | # ps a | + | [root@dhcp0-56 ovz-utils]# 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 runing |
| − | + | ("+" means that the process is foreground and small "s" means that the process is session leader, but it isn't relevant in our discussion). | |
| − | + | D state occurs then the process is in uninterruptable 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 long. | ||
| + | If you have a heap of D state processes than some logic in system is disrupt. The very important thing then 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: | ||
<pre> | <pre> | ||
| − | # ps axl | | + | [root@dhcp0-56 ~]# 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> | ||
| − | + | Then you have problem with D state processes always attach this information to the report, that you send to developers. | |
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[[Category: Troubleshooting]] | [[Category: Troubleshooting]] | ||
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