[systemd-devel] [PATCH v3 3/4] manager: add a global watchdog reboot timestamp

Lennart Poettering lennart at poettering.net
Wed Feb 1 11:05:27 PST 2012

On Wed, 01.02.12 17:17, Michael Olbrich (m.olbrich at pengutronix.de) wrote:

> This patch adds WatchdogRebootTimestamp[Monotonic] to the systemd
> manager API. It contains the earliest point in time when systemd might
> reboot the system because the timer for WatchdogRebootUSec for a
> service expired.
> If we assume the system takes Xus to shut down then
> WatchdogRebootTimestamp + Xus should never be in the past. A watchdog
> daemon handling the hardware watchdog can use this information to
> determine when to let the hardware watchdog restart the system.
> This is convenience information for a watchdog daemon. With this the
> it can avoid a lot of D-Bus calls that are necessary to calculate the
> same value.

I had a longer discussion with Kay about this the other day, i.e. how we
want the introduction of awatchdog look in the end. We kinda came to the
formula that systemd should supervise services and the hw watchdog
should supervise systemd. That way systemd would just write to the hw
watchdog in its core event loop (i.e. in PID1) but not make any
connection between the actual services and the hw watchdog. Now, your
idea seems to be that watchdog acts as a multiplexer for the hw watchdog
for services, right?

I am wondering now what the right way to handle this is in the
end. Would it make sense to drop the multiplexing thing for you, or is
there a strong case for doing this?

(As I figured out newer Intel chipsets all have watchdogs now, so I am
actually quite keen to see this implemented in systemd now, since I can
actually test it.)


Lennart Poettering - Red Hat, Inc.

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