From owner-freebsd-doc@FreeBSD.ORG Wed Nov 3 01:44:14 2004 Return-Path: Delivered-To: freebsd-doc@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1A5FA16A4CE for ; Wed, 3 Nov 2004 01:44:14 +0000 (GMT) Received: from asclepius.uwa.edu.au (asclepius3.uwa.edu.au [130.95.128.60]) by mx1.FreeBSD.org (Postfix) with ESMTP id 18D8543D49 for ; Wed, 3 Nov 2004 01:44:13 +0000 (GMT) (envelope-from zanchey@mussel.ucc.gu.uwa.edu.au) Received: from asclepius.kas (localhost.localdomain [127.0.0.1]) by asclepius.uwa.edu.au (Postfix) with SMTP id BA6B21856B8 for ; Wed, 3 Nov 2004 09:43:26 +0800 (WST) Received: from asclepius (localhost.localdomain [127.0.0.1]) by asclepius.prekas (Postfix) with SMTP id A820C18571F for ; Wed, 3 Nov 2004 09:43:26 +0800 (WST) X-UWA-Client-IP: 130.95.13.9 (UWA) Received: from mooneye.ucc.gu.uwa.edu.au (mooneye.ucc.gu.uwa.edu.au [130.95.13.9]) by asclepius.input (Postfix) with ESMTP id 9B9121856B8 for ; Wed, 3 Nov 2004 09:43:26 +0800 (WST) Received: by mooneye.ucc.gu.uwa.edu.au (Postfix, from userid 801) id E346F17F21; Wed, 3 Nov 2004 09:44:04 +0800 (WST) Received: from mussel (mussel.ucc.gu.uwa.edu.au [130.95.13.18]) by mooneye.ucc.gu.uwa.edu.au (Postfix) with ESMTP id 0A28217F20; Wed, 3 Nov 2004 09:44:04 +0800 (WST) Received: from zanchey (helo=localhost) by mussel with local-esmtp (Exim 3.36 #1 (Debian)) id 1CPABv-0000wK-00; Wed, 03 Nov 2004 09:44:03 +0800 Date: Wed, 3 Nov 2004 09:44:03 +0800 (WST) From: David Adam To: Joel Dahl In-Reply-To: <20041102183220.53DCE37E7B@smtp4-2-sn2.hy.skanova.net> Message-ID: References: <20041102183220.53DCE37E7B@smtp4-2-sn2.hy.skanova.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: David Adam X-SpamTest-Info: Profile: Formal (145/041102) X-SpamTest-Info: Profile: Detect Hard [UCS 290904] X-SpamTest-Info: Profile: SysLog X-SpamTest-Info: Profile: Marking Spam - Subject (UCS) [02-08-04] X-SpamTest-Status: Not detected X-SpamTest-Version: SMTP-Filter Version 2.0.0 [0125], KAS/Release cc: freebsd-doc@FreeBSD.org Subject: Re: docs/73429: [patch] Update Handbook, Chapter 8, kernel configuration X-BeenThere: freebsd-doc@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Documentation project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Nov 2004 01:44:14 -0000 On Tue, 2 Nov 2004, Joel Dahl wrote: > - This option causes Giant to be included in the set of mutexes > - adaptively spun on. > + Giant is the name of a mutual exclusion mechanism (a sleep mutex) > + that protects a large set of kernel resources. Today, this is an > + unacceptable performance bottleneck which is actively beeing replaced > + with locks that protect individual resources. The ADAPTIVE_GIANT > + option causes Giant to be included in the set of mutexes adaptively > + spun on. That is, when a thread wants to lock the Giant mutex, but it > + is already locked by a thread on another CPU, the first thread will > + keep running and wait for the lock to be released. Normally, the > + thread would instead go back to sleep and wait for its next chance to > + run. This is the opinion of a relative outsider, but... After reading the above (new) paragraph, I understand more about FreeBSD's internal workings, something of the future of this statement and exactly what ADAPTIVE_GIANT is. All good. Unfortunately, I really can't tell - as a relative newbie - whether that leaving it in/out is a good idea (I assume it's probably good for performance and doesn't break too much stuff, hence its inclusion in GENERIC). How about a sentence that says "If you're not sure/If you want to do X/If your mother is not a hamster, then you should leave this in/can safely comment this out."? Cheers, David Adam (member of The Great Unwashed) zanchey@ucc.gu.uwa.edu.au