From owner-freebsd-arm@FreeBSD.ORG Wed Nov 28 07:48:26 2012 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 21D9F219 for ; Wed, 28 Nov 2012 07:48:26 +0000 (UTC) (envelope-from Matthias.Reyelt@brunel.de) Received: from mailout-f3.arcor-ip.de (mailout-f3.arcor-ip.de [145.253.3.216]) by mx1.freebsd.org (Postfix) with ESMTP id AB8418FC12 for ; Wed, 28 Nov 2012 07:48:25 +0000 (UTC) Received: from mailer2.brunellocal.de (unknown [145.254.28.158]) by mailout-f3.arcor-ip.de (Arcor-IP) with ESMTP id 8A8B81B3633 for ; Wed, 28 Nov 2012 08:42:55 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by localhost (Postfix) with ESMTP id 4E2EC24942 for ; Wed, 28 Nov 2012 08:42:55 +0100 (CET) X-Virus-Scanned: amavisd-new at brunellocal.de Received: from mailer2.brunellocal.de ([127.0.0.1]) by localhost (mailer2.brunellocal.de [127.0.0.1]) (amavisd-new, port 10024) with SMTP id Wy-ZkjERRz9K for ; Wed, 28 Nov 2012 08:42:55 +0100 (CET) Received: from mail-hv.brunel.de (mail-hv.brunellocal.de [192.168.1.234]) by mailer2.brunellocal.de (Postfix) with ESMTP id 096FC23883 for ; Wed, 28 Nov 2012 08:42:55 +0100 (CET) Received: from bcslx10.bcs.brunel.local ([172.16.1.3]) by 935s02ub.brunellocal.de (Lotus Domino Release 7.0.4FP1) with ESMTP id 2012112808425206-2918 ; Wed, 28 Nov 2012 08:42:52 +0100 Received: from bcspc139.localnet (bcspc139.bcs.brunel.local [172.16.101.98]) by bcslx10.bcs.brunel.local (Postfix) with ESMTP id 53C1AFD8CB; Wed, 28 Nov 2012 08:42:52 +0100 (CET) From: Matthias Reyelt Organization: Brunel Communications To: freebsd-arm@freebsd.org Subject: Improve system latency during harddisk access Date: Wed, 28 Nov 2012 08:42:51 +0100 User-Agent: KMail/1.13.6 (Linux/2.6.37.6-0.7-desktop; KDE/4.6.0; i686; ; ) MIME-Version: 1.0 Message-Id: <201211280842.51271.Matthias.Reyelt@brunel.de> X-MIMETrack: Itemize by SMTP Server on HUB93501/Brunel/De(Release 7.0.4FP1|July 20, 2009) at 28.11.2012 08:42:52 AM, Serialize by Router on HUB10149/Brunel/De(Release 7.0.4FP2|June 06, 2010) at 28.11.2012 08:42:54 AM, Serialize complete at 28.11.2012 08:42:54 AM Content-Transfer-Encoding: 7bit Content-Type: Text/Plain; charset="us-ascii" X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Nov 2012 07:48:26 -0000 Hi, We have a cyclic test application running at a 50ms cycle running on a Marvell OpenRD with 9.0 with an attached sata harddisk. We have observed that the system is sometimes blocked up to about 18ms by accessing the harddisk. We have checked the ULE and 4BSD scheduler and preemption, but without any significant difference. I actually do not really believe that this is somewhat ARM specific. Generally, harddisk I/O is critical for latency, but I've cross checked with a Linux installed OpenRD and had less impact of harddisk I/O. Do you have any idea how to minimize the influence of harddisk I/O under FreeBSD? Regards Matthias