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List:       linux-390
Subject:    Re: Watchdog Timeout Value [SOLVED]
From:       Jorge Fábregas <jorge.fabregas () gmail ! com>
Date:       2015-09-16 0:53:15
Message-ID: 55F8BD7B.6080304 () gmail ! com
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On 09/15/2015 05:43 PM, Neale Ferguson wrote:
> The underlying CP service Diagnose x'288' takes a parameter specifying the
> time bomb interval in seconds. So it's a function of the module.
> 
> According to the source code of vmwatchdog.c there is an IOCTL that may be
> issued that will change the default of 60 to whatever value you care to
> put there. So you will need to write a small program that can issue the
> ioctl with the WDIOC_SETTIMEOUT option. You will need to #include
> <linux/watchdog.h>

Hi Neale,

Thanks for the feedback! After your post I decided to search about
IOCTLs and remembered seeing that on the logs (my watchdog application
is SBD, used for self-fencing, on SUSE High-Availability).  Now that I
see the logs carefully I see this:

ERROR: WDIOC_SETTIMEOUT: Failed to set watchdog timer to 5 seconds.:
Invalid argument

That's what I saw originally and then did a "modinfo vmwatchdog" and saw
that there were no parameters to set the timeout and I said to myself
"ahh that's why SBD can't set it".  I had no idea about an IOCTL!  Well,
it turns that that's the mechanism used by SBD (so I didn't have to
write the small C program).  I kept thinking about that "invalid
argument" part.  It turns out the minimum allowed value is 15 seconds!

I've recreated my SBD device (setting it to 15 seconds) and it worked;
changed it to 14 seconds and it fails.
So that was it.  I'm perfectly fine with 15 seconds.

Thanks a bunch for the info & hints that guided me to the solution!

All the best,
Jorge

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