Date: Tue, 26 Feb 2002 20:50:46 -0500 (EST) From: Robert Watson <rwatson@FreeBSD.ORG> To: Jorge Aldana <jorge@salk.edu> Cc: Garance A Drosihn <drosih@rpi.edu>, Bob Van Valzah <Bob@Talarian.Com>, smp@FreeBSD.ORG Subject: Re: Performance vs. Stable Message-ID: <Pine.NEB.3.96L.1020226204912.38595H-100000@fledge.watson.org> In-Reply-To: <20020226162616.E32126-100000@merckx.salk.edu>
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On Tue, 26 Feb 2002, Jorge Aldana wrote: > Why isn't WITNESS and WITNESS_SKIPSPIN in LINT? Or is it undocumented? > While I'm at it what are they, if you know. They're in NOTES, the -CURRENT equivilent of LINT. You can build LINT from NOTES by typing in: make LINT in your conf directory. Here are the entries on those settings: # SMP Debugging Options: # # MUTEX_DEBUG enables various extra assertions in the mutex code. # WITNESS enables the mutex witness code which detects deadlocks and cycles # during locking operations. # WITNESS_DDB causes the witness code to drop into the kernel debugger if # a lock heirarchy violation occurs or if locks are held when going to # sleep. # WITNESS_SKIPSPIN disables the witness checks on spin mutexes. options MUTEX_DEBUG options WITNESS options WITNESS_DDB options WITNESS_SKIPSPIN It's worth noting that WITNESS can have a dramatic impact on performance. I actually turned it off by default recently, and it got turned back on again (for good reasons). Any benchmarking must be done without those settings turned on. Robert N M Watson FreeBSD Core Team, TrustedBSD Project robert@fledge.watson.org NAI Labs, Safeport Network Services To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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