From owner-freebsd-arch Wed Dec 12 15:31:50 2001 Delivered-To: freebsd-arch@freebsd.org Received: from mass.dis.org (mass.dis.org [216.240.45.41]) by hub.freebsd.org (Postfix) with ESMTP id F227637B416 for ; Wed, 12 Dec 2001 15:31:47 -0800 (PST) Received: from mass.dis.org (localhost [127.0.0.1]) by mass.dis.org (8.11.6/8.11.3) with ESMTP id fBCNbc103644; Wed, 12 Dec 2001 15:37:38 -0800 (PST) (envelope-from msmith@mass.dis.org) Message-Id: <200112122337.fBCNbc103644@mass.dis.org> To: Terry Lambert Cc: freebsd-arch@FreeBSD.ORG Subject: Re: Real world Root Resizing (was Re: Proposed auto-sizing patch ... In-Reply-To: Message from Terry Lambert of "Wed, 12 Dec 2001 10:36:19 PST." <3C17A3A3.A439BE21@mindspring.com> Date: Wed, 12 Dec 2001 15:37:38 -0800 From: Mike Smith Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > Now say you had 99 cylinder groups, and you added one cylinder group. > Your new cylinder group is 0% fiull, and the rest are 90% full. What > is the probability that the new cylinder group will be selected for > new writes? > > The answer is 1%. Ideally, you would want to weight the choice based > on how full each cylinder group was, but that won't happen, since it > defeats the seek optimization if you do that. Actually, this isn't entirely true. The pre-dirpref code would in fact create all new directories in this new cylinder group at least until it was as full (of directories) as the other. And thus new files would also be created there. Dirpref changes this to some degree, and of course it doesn't help for files that already exist. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message