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wd_keepalive(8) [debian man page]

WD_KEEPALIVE(8) 					      System Manager's Manual						   WD_KEEPALIVE(8)

wd_keepalive - a simplified software watchdog daemon SYNOPSIS
wd_keepalive [-c filename|--config-file filename] DESCRIPTION
This is a simplified version of the watchdog daemon. If configured so it only opens .IR /dev/watchdog , and keeps writing to it often enough to keep the kernel from resetting, at least once per minute. Each write delays the reboot time another minute. After a minute of inactivity the watchdog hardware will cause a reset. In the case of the software watchdog the ability to reboot will depend on the state of the machines and interrupts. The wd_keepalive daemon can be stopped without causing a reboot if the device /dev/watchdog is closed correctly, unless your kernel is com- piled with the CONFIG_WATCHDOG_NOWAYOUT option enabled. Under high system load wd_keepalive might be swapped out of memory and may fail to make it back in in time. Under these circumstances the Linux kernel will reset the machine. To make sure you won't get unnecessary reboots make sure you have the variable realtime set to yes in the configuration file watchdog.conf. This adds real time support to wd_keepalive: it will lock itself into memory and there should be no problem even under the highest of loads. On system running out of memory the kernel will try to free enough memory by killing process. The wd_keepalive daemon itself is exempted from this so-called out-of-memory killer. OPTIONS
Available command line options are the following: -c config-file, --config-file config-file Use config-file as the configuration file instead of the default /etc/watchdog.conf. FILES
/dev/watchdog The watchdog device. /var/run/ The pid file of the running wd_keepalive. SEE ALSO
watchdog.conf(5) watchdog(8) 4th Berkeley Distribution January 2005 WD_KEEPALIVE(8)

Check Out this Related Man Page

WATCHDOG(9)						   BSD Kernel Developer's Manual					       WATCHDOG(9)

watchdog -- software and hardware watchdog facility SYNOPSIS
#include <sys/watchdog.h> void watchdog_fn(void *private, u_int cmd, int *error); EVENTHANDLER_REGISTER(watchdog_list, watchdog_fn, private, 0); EVENTHANDLER_DEREGISTER(watchdog_list, eventhandler_tag); DESCRIPTION
To implement a watchdog in software or hardware, only a single function needs to be written and registered on the global watchdog_list. The function must examine the cmd argument and act on it as follows: If cmd is zero, the watchdog must be disabled and the error argument left untouched. If the watchdog cannot be disabled, the error argument must be set to EOPNOTSUPP. Else the watchdog should be reset and configured to a timeout of (1 << (cmd & WD_INTERVAL)) nanoseconds or larger and the error argument be set to zero to signal arming of a watchdog. If the watchdog cannot be configured to the proposed timeout, it must be disabled and the error argument left as is (to avoid hiding the arm- ing of another watchdog). There is no specification of what the watchdog should do when it times out, but a hardware reset or similar ``drastic but certain'' behaviour is recommended. SEE ALSO
watchdog(4) AUTHORS
The watchdog facility and this manual page was written Poul-Henning Kamp <>. BSD
February 28, 2004 BSD
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