From owner-freebsd-stable Sat Feb 19 2:26: 2 2000 Delivered-To: freebsd-stable@freebsd.org Received: from fw.wintelcom.net (ns1.wintelcom.net [209.1.153.20]) by hub.freebsd.org (Postfix) with ESMTP id 23CB937BBB3 for ; Sat, 19 Feb 2000 02:25:50 -0800 (PST) (envelope-from bright@fw.wintelcom.net) Received: (from bright@localhost) by fw.wintelcom.net (8.9.3/8.9.3) id CAA16544; Sat, 19 Feb 2000 02:54:19 -0800 (PST) Date: Sat, 19 Feb 2000 02:54:19 -0800 From: Alfred Perlstein To: "Jeffrey J. Mountin" Cc: Tom , stable@FreeBSD.ORG Subject: Re: Initial performance testing w/ postmark & softupdates... Message-ID: <20000219025419.O21720@fw.wintelcom.net> References: <38ACAF8B.65E314E9@newsguy.com> <3.0.3.32.20000219035342.009ce460@207.227.119.2> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i In-Reply-To: <3.0.3.32.20000219035342.009ce460@207.227.119.2>; from jeff-ml@mountin.net on Sat, Feb 19, 2000 at 03:53:42AM -0600 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG * Jeffrey J. Mountin [000219 02:24] wrote: > At 03:08 PM 2/18/00 -0800, Tom wrote: > >On Fri, 18 Feb 2000, Daniel C. Sobral wrote: > > > >> Tom wrote: > >> > > >> > Not really. You could just use async updates instead of softupdates. > >> > Or an OS that uses async updates. Write caching metadata is always > faster > >> > than re-ordering it intelligently. > >> > >> Softupdates reduces the number of writes needed. It can coalesce writes > >> to the same block. > > > > Async updates are always as fast as softupdates, if not faster. You > >should read the softupdates docs. > > As fast, but not safer. Depending on the actual situation, softdep can out perform full async because the way it intellegently recognizes things that don't happen and does a better job at delaying rapidly changing meta-data from hitting disk. > Can't recall the entire analogy, but Terry mentioned on -hacker a long time > back something to the effect that softupdates is like having a seatbelt and > an airbag rather than just a seatbelt, as well as a faster car too. The effect of softdep is basically the safeness of a normal mount however with the speed of async. -Alfred To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message