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Cc: freebsd-hackers@freebsd.org
Subject: Re: reason for "magic" crashes.
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>>
>>
>> There is nothing in cron that is done at sunday.
>>
>> i don't run "periodic" stuff in /etc/crontab
>>
>
> Compile the kernel with the following:
>
> makeoptions     DEBUG="-O0 -g"
>
> options         KDB                     # Enable kernel debugger support.
> options         DDB                     # Support DDB.
> options         GDB                     # Support remote GDB.
> options         DEADLKRES               # Enable the deadlock resolver
> options         INVARIANTS              # Enable calls of extra sanity checking
> options         INVARIANT_SUPPORT       # Extra sanity checks of internal structures, required by INVARIANTS
> options         WITNESS                 # Enable checks to detect deadlocks and cycles
> options         WITNESS_SKIPSPIN        # Don't run witness on spinlocks for speed
> options         DIAGNOSTIC
>
> After kernel panic ddb prompt will be waiting for you. Type in:
> dump <enter>
> reset <enter>
>
> Make sure you have swap that can handle crashdumps.

already did this part and debug part, but not DDB. As you see - hang not 
crashdump

how much would it slow down whole thing?

If less than 2 times it can be - CPU are rerely half loaded