Date: Sun, 24 Jun 2012 21:08:53 +0200 From: Mateusz Guzik <mjguzik@gmail.com> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> Cc: freebsd-hackers@freebsd.org Subject: Re: reason for "magic" crashes. Message-ID: <20120624190853.GB15899@dft-labs.eu> In-Reply-To: <alpine.BSF.2.00.1206242049230.73675@wojtek.tensor.gdynia.pl> References: <20120623162415.303430@gmx.com> <alpine.BSF.2.00.1206231947160.40095@wojtek.tensor.gdynia.pl> <alpine.BSF.2.00.1206241856090.73001@wojtek.tensor.gdynia.pl> <20120624180526.GA15899@dft-labs.eu> <alpine.BSF.2.00.1206242049230.73675@wojtek.tensor.gdynia.pl>
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On Sun, Jun 24, 2012 at 08:50:41PM +0200, Wojciech Puchar wrote: > >> > >> > >>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 Are you asking about overhead of DDB or all debug options? I don't think that DDB support can be accounted for slowdown. As for the rest, it's hard to say. I guess it depends on your workload, also I never performed any benchmarks to compare this and I'm unaware of any. In other words, you have to test it yourself. -- Mateusz Guzik <mjguzik gmail.com>
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