The watchdog package provides a user-space application which can be configured to provide updates to a hardware or software watchdog timer via the Linux kernel’s watchdog interface.

In addition to the standard provisions of watchdog timer behavior, the watchdog package can be configured to voluntarily cease operation based on a number of administrator-defined heuristics.

watchdog

[[email protected] ~]# ps -ef | grep watchdog
root         6     2  0 Oct17 ?        00:00:00 [watchdog/0]
root        10     2  0 Oct17 ?        00:00:00 [watchdog/1]
root        14     2  0 Oct17 ?        00:00:00 [watchdog/2]
root        18     2  0 Oct17 ?        00:00:00 [watchdog/3]
root        22     2  0 Oct17 ?        00:00:00 [watchdog/4]
root        26     2  0 Oct17 ?        00:00:00 [watchdog/5]
root        30     2  0 Oct17 ?        00:00:00 [watchdog/6]
root        34     2  0 Oct17 ?        00:00:00 [watchdog/7]
root        38     2  0 Oct17 ?        00:00:00 [watchdog/8]
root        42     2  0 Oct17 ?        00:00:00 [watchdog/9]
root        46     2  0 Oct17 ?        00:00:00 [watchdog/10]
root        50     2  0 Oct17 ?        00:00:00 [watchdog/11]
root     16881 16304  0 11:23 pts/1    00:00:00 grep watchdog

stop watchdog

[[email protected] ~]# cat /proc/sys/kernel/nmi_watchdog 
[[email protected] ~]# echo 0 > /proc/sys/kernel/nmi_watchdog 
[[email protected] ~]# ps -ef | grep watchdog
root     16894 16304  0 11:24 pts/1    00:00:00 grep watchdog

To start monitoring the system with OProfile, execute the following command as root:

~]# opcontrol --start

Output similar to the following is displayed:

Using log file /var/lib/oprofile/oprofiled.log Daemon started. Profiler running.
The settings in /root/.oprofile/daemonrc are used.
The OProfile daemon, oprofiled, is started; it periodically writes the sample data to the /var/lib/oprofile/samples/ directory. The log file for the daemon is located at /var/lib/oprofile/oprofiled.log.
Disable the nmi_watchdog registers

On a Red Hat Enterprise Linux 6 system, the nmi_watchdog registers with the perf subsystem. Due to this, the perf subsystem grabs control of the performance counter registers at boot time, blocking OProfile from working.

To resolve this, either boot with the nmi_watchdog=0 kernel parameter set, or run the following command to disable nmi_watchdog at run time:

~]# echo 0 > /proc/sys/kernel/nmi_watchdog

To re-enable nmi_watchdog, use the following command:

~]# echo 1 > /proc/sys/kernel/nmi_watchdog

To stop the profiler, execute the following command as root:

~]# opcontrol --shutdown

reference



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Published

21 October 2013

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