From owner-freebsd-fs@FreeBSD.ORG Wed Feb 15 15:35:16 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B7395106564A for ; Wed, 15 Feb 2012 15:35:16 +0000 (UTC) (envelope-from devgs@ukr.net) Received: from ffe1.ukr.net (ffe1.ukr.net [195.214.192.43]) by mx1.freebsd.org (Postfix) with ESMTP id 5F0BB8FC0A for ; Wed, 15 Feb 2012 15:35:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ukr.net; s=ffe; h=Date:Message-Id:From:To:References:In-Reply-To:Subject:Cc:Content-Type:Content-Transfer-Encoding:MIME-Version; bh=TKFYtQtc7yiL5F5mwYWwz+JDK9MQSmYNHz0TvdkuP6M=; b=P4aYJjCXfeoFZLUgwGe8zfZztPr7MFk8nYJATK52FrWlByFWFZgL55P9sUttI54/sNxLve9Rg9XUKt8WOYyKs4JUasf+GaBdHLcsJDZZ6Sz/sK6FdzkJSSujiaDL2xk48h326/Gsh/GbQZqRemiGq9m2Yk1ekyzjjcEnw5ds1OE=; Received: from mail by ffe1.ukr.net with local ID 1Rxgt0-000Anl-L5 ; Wed, 15 Feb 2012 17:35:14 +0200 MIME-Version: 1.0 In-Reply-To: References: <70229.1329318412.9319724204137054208@ffe16.ukr.net> To: "George Kontostanos" From: "Pavlo" X-Mailer: freemail.ukr.net 4.0 X-Originating-Ip: [212.42.94.154] Message-Id: <41082.1329320114.6955040073494560768@ffe1.ukr.net> X-Browser: Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:10.0.1) Gecko/20100101 Firefox/10.0.1 Date: Wed, 15 Feb 2012 17:35:14 +0200 Content-Type: text/plain; charset="windows-1251" Content-Transfer-Encoding: binary Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-fs@freebsd.org Subject: Re: ZFS and mem management X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Feb 2012 15:35:16 -0000 > 2012/2/15 Pavlo : > > > >>On 15/02/2012 13:39, Pavlo wrote: >>> > >>> >> >> Unfortunately we can't afford disabling prefetch. It is too much of an>> overhead.>> >> Also I made some tests. I have process that maps file using mmap() and>> writes or reads first byte of each page of mapped file with some data.> >>Note that ZFS is designed so that it interacts somewhat badly with >>mmap() and other kernel services which rely on coherency between VM and >>IO such as sendfile(). At the very best, you will have two in-kernel >>copies of all data buffers used with such interfaces, but there have >>been sporadic reports that there are other bugs with it. >> >>If you have a test server, I'd recommend you do the same test on UFS for >>comparison. > > Was going to try this... Thanks for reply. > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" Why do you think that disabling prefetch is an overhead? -- George Kontostanos Aicom telecoms ltdhttp://www.aisecure.net > Well... not me though. System administrator >_> . I suppose because we have a big IO traffic.