From owner-freebsd-scsi@FreeBSD.ORG Mon Nov 17 10:18:30 2014 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 8C3CC1A1 for ; Mon, 17 Nov 2014 10:18:30 +0000 (UTC) Received: from BLU004-OMC1S20.hotmail.com (blu004-omc1s20.hotmail.com [65.55.116.31]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (Client CN "*.outlook.com", Issuer "MSIT Machine Auth CA 2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 48D35DC5 for ; Mon, 17 Nov 2014 10:18:30 +0000 (UTC) Received: from BLU436-SMTP193 ([65.55.116.8]) by BLU004-OMC1S20.hotmail.com over TLS secured channel with Microsoft SMTPSVC(7.5.7601.22751); Mon, 17 Nov 2014 02:17:23 -0800 X-TMN: [XiOX57omw15S30YTDhrOX6CaM8zPINZ9] X-Originating-Email: [moremore2@outlook.com] Message-ID: Date: Mon, 17 Nov 2014 18:17:17 +0800 From: k simon User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: freebsd-scsi@freebsd.org Subject: HDD slow down in heavy load Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 17 Nov 2014 10:17:22.0966 (UTC) FILETIME=[AD76CB60:01D0024F] X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Nov 2014 10:18:30 -0000 Hi, List, I observed sometimes DragonflyBSD do much better than FB in heavy load , eg. squid or zabbix's postgresql database. The difference may related to DFBSD have enhanced CAM DA driver to separate read and write streams, allowing concurrent write completion in the face of many stalled read requests. It's released within DFBSD V2.10 at 2011: http://leaf.dragonflybsd.org/mailarchive/commits/2011-04/msg00062.html http://leaf.dragonflybsd.org/mailarchive/commits/2011-04/msg00061.html I guess I'm alone for notice it. Regards Simon