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Date:      Sat, 30 Aug 1997 21:25:34 +0200
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Steve Passe <smp@csn.net>
Cc:        smp@freebsd.org
Subject:   Re: HEADS UP: another set of changes. 
Message-ID:  <7370.872969134@critter.freebsd.dk>
In-Reply-To: Your message of "Sat, 30 Aug 1997 12:03:16 MDT." <199708301803.MAA16417@Ilsa.StevesCafe.com> 

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In message <199708301803.MAA16417@Ilsa.StevesCafe.com>, Steve Passe writes:
>Hi,
>
>> >We're at the point where deadlocks are going to become common.  Bear with m
>e
>> >and help as you can.  When you hit one please record all the facts you can,
>> >and report them to smp@freebsd.org.  Hopefully we will get thru this period
>> >before too long...
>> 
>> I pressume that we want to instrument simplelock carefully in the
>> #ifdef DIAGNOSTIC case ?
>
>It would be really nice, any one with ideas along that line please speak
>up (or go for it!).
>
>One idea I had was to use the local timer as a watchdog.  set it for 10 second
>s
>going into a simplelock. if your not out by then if fires a high priority
>interrupt that causes a panic.  the SMP disable_intr() would have to be 
>reworked a little, and there are probably other areas like ISRs that would
>ignore it, but it should help some of the time.

Well, I was thinking more about making it a counting semaphore in that
case and printf a warning if the count was unexpected.

I know for almost for sure that it will trigger in the vfs/vnode stuff
because of nested calls.

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."



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