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Sender: Alexander Motin <mavbsd@gmail.com>
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Date: Tue, 20 Sep 2011 23:04:55 +0300
From: Alexander Motin <mav@FreeBSD.org>
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To: Andriy Gapon <avg@FreeBSD.org>
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Cc: hackers@FreeBSD.org
Subject: Re: SW_WATCHDOG vs new eventtimer code
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Hi.

On 20.09.2011 22:19, Andriy Gapon wrote:
> just want to check with you first if the following makes sense.
> I use SW_WATCHDOG on one of the test machines, which was recently updated to
> from stable/8 to head.  Now it seems to get seemingly random watchdog events.
> My theory is that this is because of the eventtimer logic.
> If during idle period we accumulate enough timer ticks and then run all those
> ticks very rapidly, then the SW_WATCHDOG code may get an impression that it was
> not patted for many real ticks.
> Not sure what would be the best way to make SW_WATCHDOG happier/smarter.

Eventtimer code now set to generate interrupts at least 4 times per
second for each CPU. As soon as SW_WATCHDOG only handles periods more
then one second, I would say it should not be hurt. I would try to add
some debug there to see what's going on (how big the tick busts are).
I'll try it to do it tomorrow.

-- 
Alexander Motin