On Thu, Jun 6, 2013 at 10:11 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > 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. Sorry, I will wait. > > 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
