From owner-freebsd-hackers Sun May 27 20: 1:22 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from spnet.com (m42.spnet.com [207.181.251.42]) by hub.freebsd.org (Postfix) with ESMTP id 529FC37B423 for ; Sun, 27 May 2001 20:01:19 -0700 (PDT) (envelope-from elh_fbsd@spnet.com) Received: from spnet.com (m3.spnet [192.168.76.3]) by spnet.com (8.9.3/8.8.5) with ESMTP id UAA48350; Sun, 27 May 2001 20:01:18 -0700 (PDT) Message-Id: <200105280301.UAA48350@spnet.com> X-Mailer: exmh version 2.3.1 01/18/2001 with nmh-1.0.4 To: hackers@FreeBSD.ORG Subject: Re: general speed differences between 4.1.1-RELEASE and 4.3-RELEASE In-Reply-To: Message from Rik van Riel of "Sun, 27 May 2001 22:25:45 -0300." Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 27 May 2001 20:01:18 -0700 From: Ed Hudson Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > I doubt FreeBSD would need to enable write caching in order > to be as fast as Linux (which doesn't have write caching i spoke too harshly. what i meant to show is that interactive performance is compromised under load with soft updates enabled (although soft updates clearly speed up some general tasks and accelerate some tasks considerably). i also i wanted to show that hw.ata.wc=0 has 3-7x impact on fast hardware, which is a much larger impact than almost any other single parameter. i had seen soft updates as a justification of turning ata.wc off (later education on my part by the memebers of hackers has broadened my understanding of the motivation). i suspect that this issue was well hashed out in this news group when i wasn't tracking the stream. i use freebsd to help design the chips that i work on, and i've always relied on and been impressed by its ability to perform well handling large cad programs - so i was just surprised at the sudden change in this default behavior re hw.ata.wc=0. clearly, this was just ignorance on my part, and i suspect had i looked more closely at the release notes i would have just turned this parameter on, kept soft-updates off and still been a happy camper. (much kudoo's to mr. dillons now timely tuning.7, btw). another note regarding hw.ata.wc=0 as the default - if i assume that i've been running effectively with hw.ata.wc=1 for the last couple of years, i would extrapolate that the likelyhood of a fbsd/ufs failure in this mode is small compared to the reliability problems of the rest of the system, and the same protection that covers those liabilities also cover my exposure to hw.ata.wc=1 problems (e.g., good backups, ups's, etc). given the huge impact that users (at least those like myself) see of this parameter, and the reliability impact that i think i understand, i am surprised by the choice of default. it feels like a recruiting attempt for linux. (btw, i do think that the freebsd project is probably the best working example of open source software, and its benefits, so i'm not trying to promote linux - but both have benefited from their coevolution). (system reliability: - i think hard drive failures are maybe #1 in occurance, motherboard and memory failures as #2, and pwr supply failures #3, and cpu failures last.) ok, i know the knobs to turn to solve my problems. i'm happy. i'll shutup. thanks again to all you hackers for a great os. i guess there really aren't evil space monsters invading the inner sanctum... -elh To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message