Hello Wim Van, Can you look into below? 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
