Date: Wed, 10 Mar 1999 12:10:45 -0700 (MST) From: "Kenneth D. Merry" <ken@plutotech.com> To: dillon@apollo.backplane.com (Matthew Dillon) Cc: Thierry.Besancon@lps.ens.fr, luoqi@watermarkgroup.com, Thierry.Besancon@tournesol.lps.ens.fr, dwhite@gdi.uoregon.edu, freebsd-smp@FreeBSD.ORG, Pierre.David@prism.uvsq.fr, alc@cs.rice.edu, jt@ratp.fr Subject: Re: lockmgr() panic Message-ID: <199903101910.MAA09630@panzer.plutotech.com> In-Reply-To: <199903101850.KAA56970@apollo.backplane.com> from Matthew Dillon at "Mar 10, 1999 10:50:36 am"
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Matthew Dillon wrote...
>
> :>> This is a completely different problem.
> :
> :Life sucks today.
> :
> :Reading src/sys/kern/kern_lock.c, I saw this piece of code that might
> :be relevant with this problem :
> :
> :#if !defined(MAX_PERF)
> : if ((extflags & LK_CANRECURSE) == 0)
> : panic("lockmgr: locking against myself");
> :#endif
> :
> :Before defining the flag, does anybody know what MAX_PERF implies
> :other than not panicing the kernel ? What does it means ?
>
> MAX_PERF means 'maximum performance'. Note that the conditional
> is an '#if !defined ...' conditional, not an '#if defined ...'
> conditional.
>
> This means that by default, when MAX_PERF is *not* defined, the above
> code *will* be executed.
>
> If MAX_PERF is defined, the system removes many sanity checks from the
> kernel that would otherwise be compiled in. I would recommend that you
> *NOT* define it.
>
> -Matt
I'll second this. One of the few times I've really seriously hosed my
filesystem came one time a couple of years ago (Summer '97) when I defined
MAX_PERF.
Even during the early CAM development, I never managed to hose my
filesystem, but defining MAX_PERF was a really bad idea.
I think that's one of those "John-Dyson-only" options.
Ken
--
Kenneth Merry
ken@plutotech.com
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