From owner-freebsd-hackers@FreeBSD.ORG Sat Oct 23 14:10:51 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 06ECB16A4CE for ; Sat, 23 Oct 2004 14:10:51 +0000 (GMT) Received: from smtp.des.no (flood.des.no [217.116.83.31]) by mx1.FreeBSD.org (Postfix) with ESMTP id B666643D58 for ; Sat, 23 Oct 2004 14:10:50 +0000 (GMT) (envelope-from des@des.no) Received: by smtp.des.no (Pony Express, from userid 666) id C97275311; Sat, 23 Oct 2004 16:10:49 +0200 (CEST) Received: from dwp.des.no (des.no [80.203.228.37]) by smtp.des.no (Pony Express) with ESMTP id 8D2E35310; Sat, 23 Oct 2004 16:10:42 +0200 (CEST) Received: by dwp.des.no (Postfix, from userid 2602) id 3B4A0B861; Sat, 23 Oct 2004 16:10:42 +0200 (CEST) To: Clifton Royston References: <20041022223238.GA12502@tikitechnologies.com> From: des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=) Date: Sat, 23 Oct 2004 16:10:41 +0200 In-Reply-To: <20041022223238.GA12502@tikitechnologies.com> (Clifton Royston's message of "Fri, 22 Oct 2004 12:32:40 -1000") Message-ID: User-Agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (berkeley-unix) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.64 (2004-01-11) on flood.des.no X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=AWL autolearn=no version=2.64 cc: hackers@freebsd.org Subject: Re: Relative performance of swap-backed MFS vs. regular UFS? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 Oct 2004 14:10:51 -0000 Clifton Royston writes: > For a large temporary file system which must hold short-lived files, > mostly small but occasionally several very large ones (e.g. 100MB+), is > it better for performance and stability if this file system: > > 1) resides on a swap-backed MFS and trusts the OS to swap out > low-priority blocks if needed under RAM pressure, or > > 2) on a regular UFS and trusts the OS to buffer as many blocks as > possible into RAM when RAM is free? the former, provided you have enough RAM. A swap-backed MFS will only swap out when it has to, while a UFS will always write out changes after a while. > I temporarily enlarged it to 256MB which is working, but as I worked > out the worst case scenario, I realized it really would need to be > nearly 1GB to handle multiple zip-bombs each hitting the 100MB size > limit. This makes me wonder if it's wise to specify a 1GB MFS on a > system with only 1GB RAM, or wiser to just revert to a regular file > system? RAM is cheap. Toss in a couple extra gig and set up a 2 GB MFS. DES --=20 Dag-Erling Sm=F8rgrav - des@des.no