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Old 02-09-2010, 01:57 PM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Tue, 09 Feb 2010, Michael Meskes wrote:
> TOn Mon, Feb 08, 2010 at 11:44:55PM -0200, Henrique de Moraes Holschuh wrote:
> > And while at it, change wd_keepalive and watchdog to default to pat at 1Hz
> > instead of 0.1Hz. That will reduce a _lot_ the changes of spurious
> > reboots.
>
> This looks like a workaround for some other problem to me. Patting at 0.1Hz
> should be sufficient if the kernel expects a change at 0.016 Hz. I don't have
> any report about a spurious reboot, but if you do have some I'd like to learn
> more about it to see where this problem stems from.

The kernel drivers don't always expect pats at 0.016Hz by default. Some
drivers have different defaults, and as far as I recall, some of them
default to whatever the BIOS or BMC programmed in the watchdog.

A period of 1s would be a much safer default on the userland side.

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


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Old 02-09-2010, 02:02 PM
Mark Brown
 
Default why are the watchdog drivers blacklisted?

On Tue, Feb 09, 2010 at 12:57:29PM -0200, Henrique de Moraes Holschuh wrote:
> On Tue, 09 Feb 2010, Michael Meskes wrote:

> > This looks like a workaround for some other problem to me. Patting at 0.1Hz
> > should be sufficient if the kernel expects a change at 0.016 Hz. I don't have
> > any report about a spurious reboot, but if you do have some I'd like to learn
> > more about it to see where this problem stems from.

> The kernel drivers don't always expect pats at 0.016Hz by default. Some
> drivers have different defaults, and as far as I recall, some of them
> default to whatever the BIOS or BMC programmed in the watchdog.

This is definitely the case for embedded drivers, they'll generally
inherit the configuration that the hardware has. For many devices a
timeout as long as 10s may not even be possible in the hardware.


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Old 02-09-2010, 02:29 PM
Michael Meskes
 
Default why are the watchdog drivers blacklisted?

On Mon, Feb 08, 2010 at 08:54:23PM +0100, Guillem Jover wrote:
> The OOM killer can be disabled for precious processes by writting the
> string "-17" to “/proc/<pid>/oom_adj”.

Added in git. Thanks for the hint.

Michael
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Old 02-09-2010, 03:44 PM
Michael Meskes
 
Default why are the watchdog drivers blacklisted?

On Tue, Feb 09, 2010 at 12:57:29PM -0200, Henrique de Moraes Holschuh wrote:
> The kernel drivers don't always expect pats at 0.016Hz by default. Some

That's what it was years ago.

> drivers have different defaults, and as far as I recall, some of them
> default to whatever the BIOS or BMC programmed in the watchdog.
>
> A period of 1s would be a much safer default on the userland side.

Okay, will change.

Michael
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Old 02-09-2010, 04:36 PM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Tue, 09 Feb 2010, Michael Meskes wrote:
> > drivers have different defaults, and as far as I recall, some of them
> > default to whatever the BIOS or BMC programmed in the watchdog.
> >
> > A period of 1s would be a much safer default on the userland side.
>
> Okay, will change.

Thanks.

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


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Old 02-11-2010, 08:27 AM
Michael Meskes
 
Default why are the watchdog drivers blacklisted?

> If you want to test forking ability just enable test-binary test without giving
> it a test-binary or use an empty one. This will make watchdog fork() and react
> if not possible.

Thinking about this some more, the test for an emtpy test-binary is done
*after* the fork, so it should find the forking problem even without a manual
test-binary configuration. I do remember testing this feature and it worked. So
maybe you had another problem on your system. If you can reproduce this please
tell me.

Michael

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Old 02-18-2010, 05:43 PM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Mon, 08 Feb 2010, Henrique de Moraes Holschuh wrote:
> On Tue, 09 Feb 2010, Darren Salt wrote:
> > I demand that Guillem Jover may or may not have written...
> > > On Mon, 2010-02-08 at 20:15:30 +0100, Michael Meskes wrote:
> > >> Please keep in mind the OOM killer will only influence watchdog if it
> > >> happens to kill it. If you happen to run out of memory though, you can
> > >> tell watchdog to test if enough free mem is available.
> >
> > > The OOM killer can be disabled for precious processes by writting the
> > > string "-17" to ???/proc/<pid>/oom_adj???.
> >
> > That sounds to me like a good thing to do by default.
>
> And while at it, change wd_keepalive and watchdog to default to pat at 1Hz
> instead of 0.1Hz. That will reduce a _lot_ the changes of spurious
> reboots.

For the record, the watchdog daemon seems not to be able to deal with 1Hz
cleanly (must have something to do with these zombies it likes to keep
around for 1s) in my test boxes. It can do 0.5Hz just fine though.

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


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Old 02-19-2010, 07:44 AM
Michael Meskes
 
Default why are the watchdog drivers blacklisted?

> For the record, the watchdog daemon seems not to be able to deal with 1Hz
> cleanly (must have something to do with these zombies it likes to keep
> around for 1s) in my test boxes. It can do 0.5Hz just fine though.

The latest upload 5.7-4 or an older version? The older versions use sleep()
which sleep for half the interval which with 1Hz is 0 seconds. I thought I
fixed that in -4, if not please give me some details.

Michael

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Old 02-19-2010, 12:09 PM
Henrique de Moraes Holschuh
 
Default why are the watchdog drivers blacklisted?

On Fri, 19 Feb 2010, Michael Meskes wrote:
> > For the record, the watchdog daemon seems not to be able to deal with 1Hz
> > cleanly (must have something to do with these zombies it likes to keep
> > around for 1s) in my test boxes. It can do 0.5Hz just fine though.
>
> The latest upload 5.7-4 or an older version? The older versions use sleep()

Probably an older version, I don't recall if I tested it in Lenny or Squeeze
(but I do know I didn't test with Sid's version).

Any chances of uploading the new version (after it has stabilized and made
it to testing) to backports.org?

--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh


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Old 02-19-2010, 02:08 PM
Michael Meskes
 
Default why are the watchdog drivers blacklisted?

> Any chances of uploading the new version (after it has stabilized and made
> it to testing) to backports.org?

Sure, I'm currently just waiting for it to migrate.

Michael
--
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