From owner-freebsd-chat Wed Jul 14 19:27:52 1999 Delivered-To: freebsd-chat@freebsd.org Received: from smtp03.primenet.com (smtp03.primenet.com [206.165.6.133]) by hub.freebsd.org (Postfix) with ESMTP id C20C01547F for ; Wed, 14 Jul 1999 19:27:50 -0700 (PDT) (envelope-from tlambert@usr07.primenet.com) Received: (from daemon@localhost) by smtp03.primenet.com (8.8.8/8.8.8) id TAA20130; Wed, 14 Jul 1999 19:27:36 -0700 (MST) Received: from usr07.primenet.com(206.165.6.207) via SMTP by smtp03.primenet.com, id smtpd020079; Wed Jul 14 19:27:27 1999 Received: (from tlambert@localhost) by usr07.primenet.com (8.8.5/8.8.5) id TAA12176; Wed, 14 Jul 1999 19:27:21 -0700 (MST) From: Terry Lambert Message-Id: <199907150227.TAA12176@usr07.primenet.com> Subject: Re: Known MMAP() race conditions ... ? To: davids@webmaster.com (David Schwartz) Date: Thu, 15 Jul 1999 02:27:20 +0000 (GMT) Cc: markov@globalnet.co.uk, regnauld@ftf.net, chat@FreeBSD.ORG In-Reply-To: <000201bece48$2778d4f0$021d85d1@youwant.to> from "David Schwartz" at Jul 14, 99 03:28:10 pm X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > I guess it depends how full the partition is. My 2.5GB has >2GB of > > data on it, not a lot of elbow room for Diskeeper to work with. > > My recollection is that Microsoft recommends that you keep your NTFS > partitions less than half full to 'solve' this problem. Somewhat like FFS recommends a 15% reserve, and used to compromise for a little fragmentation by reducing that to 10%. Effectively, block selection in FFS is a hashing operation, and as anyone who has read Knuth's "Seminumerical Algorithms: Sorting and Searching" should be able to tell you, has operations degrade rapidly, even with a "perfect hash", after 85% fill. Whoever set the current default to 8% made a similar fragmentation vs. free reserve trade (I hope it was done while conscious of the actual trade-off being made, given that "the steady state of disks is full"). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message