From owner-freebsd-smp Tue Feb 26 17:51:25 2002 Delivered-To: freebsd-smp@freebsd.org Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by hub.freebsd.org (Postfix) with ESMTP id E905A37B400 for ; Tue, 26 Feb 2002 17:51:21 -0800 (PST) Received: from fledge.watson.org (fledge.pr.watson.org [192.0.2.3]) by fledge.watson.org (8.11.6/8.11.5) with SMTP id g1R1okD40011; Tue, 26 Feb 2002 20:50:47 -0500 (EST) (envelope-from robert@fledge.watson.org) Date: Tue, 26 Feb 2002 20:50:46 -0500 (EST) From: Robert Watson X-Sender: robert@fledge.watson.org To: Jorge Aldana Cc: Garance A Drosihn , Bob Van Valzah , smp@FreeBSD.ORG Subject: Re: Performance vs. Stable In-Reply-To: <20020226162616.E32126-100000@merckx.salk.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org 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