On Thu, Jun 06, 2013 at 08:30:01AM +0530, anish singh wrote: > Hello Wim Van, > Can you look into below? > Please be patient. Wim tends to be busy. Guenter > On Wed, Jun 5, 2013 at 8:39 AM, anish singh <anish198519851985@xxxxxxxxx> wrote: > > Hello Wim Van Sabroeck, > > Can I get your inputs on this? > > > > On Tue, Jun 4, 2013 at 8:39 AM, anish singh <anish198519851985@xxxxxxxxx> wrote: > >> On Tue, Jun 4, 2013 at 3:55 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > >>> On Mon, Jun 03, 2013 at 10:23:04PM +0530, anish singh wrote: > >>>> On Mon, Jun 3, 2013 at 8:57 PM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > >>>> > On Sun, Jun 02, 2013 at 03:43:07PM +0530, anish kumar wrote: > >>>> >> Certain watchdog drivers use a timer to keep kicking the watchdog at > >>>> >> a rate of 0.5s (HZ/2) untill userspace times out.They do this as > >>>> >> we can't guarantee that watchdog will be pinged fast enough > >>>> >> for all system loads, especially if timeout is configured for > >>>> >> less than or equal to 1 second(basically small values). > >>>> >> > >>>> >> As suggested by Wim Van Sebroeck & Guenter Roeck we should > >>>> >> add this functionality of individual watchdog drivers in the core > >>>> >> watchdog core. > >>>> >> > >>>> >> Signed-off-by: anish kumar <anish198519851985@xxxxxxxxx> > >>>> > > >>>> > Not exactly what I had in mind. My idea was to enable the softdog only if > >>>> > the hardware watchdog's maximum timeout was low (say, less than a couple > >>>> > of minutes), and if a timeout larger than its maximum value was configured. > >>>> > >>>> watchdog_timeout_invalid wouldn't this check will fail if the user space tries > >>>> to set maximum timeout more that what driver can support?It would work > >>>> for pika_wdt.c as it is old watchdog driver and doesn't register with watchdog > >>>> framwork but new drivers has to pass this api. > >>>> > >>>> OR > >>>> > >>>> Do you want to remove this check and go as explained by you?I would > >>>> favour this approach though. > >>>> > >>> One would still have a check, but the enforced limits would no longer be > >>> the driver limits, but larger limits implemented in the watchdog core. > >> How much larger would be the big question here?Should it be configurable > >> property(sysfs?) or some hardcoding based on existing drivers? > >> > >> Before going for next patch, it would be better for me to wait for some > >> more comments. > >>> > >>>> > In that case, I would have set the hardware watchdog to its maximum value > >>>> > and use the softdog to ping it at a rate of, say, 50% of this maximum. > >>>> > > >>>> > If userspace would not ping the watchdog within its configured value, > >>>> > I would stop pinging the hardware watchdog and let it time out. > >>>> > >>>> One more question.Why is the return value of watchdog_ping int? Anyway > >>>> we discard it. > >>> > >>> I can not answer that question. > >>> > >>> Guenter > -- > To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
