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. > > 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
