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
