From owner-svn-src-head@FreeBSD.ORG Sun Dec 6 12:37:20 2009 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D28E1106566B; Sun, 6 Dec 2009 12:37:20 +0000 (UTC) (envelope-from mavbsd@gmail.com) Received: from mail-bw0-f213.google.com (mail-bw0-f213.google.com [209.85.218.213]) by mx1.freebsd.org (Postfix) with ESMTP id 091658FC15; Sun, 6 Dec 2009 12:37:19 +0000 (UTC) Received: by bwz5 with SMTP id 5so2868123bwz.3 for ; Sun, 06 Dec 2009 04:37:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :user-agent:mime-version:to:cc:subject:references:in-reply-to :x-enigmail-version:content-type:content-transfer-encoding; bh=hEQ73H6y1fx+xltqPWetrD1g1l4ddCIsiPLYFY7Uypo=; b=QphF2WtmmpCDtKaVqzg0NtYwLgzAYt+7DleOmEQk8EPS1y7eh/i9NYyZY1W63Q1CgN 6zSgZiAZgnFJAEXEpgQXzoilGJ4OHsY5SKbPCuVXn4rji2gkkAtFUXfWKOCt25Ydu5/t Ng0p9+BibG6RrZYWhVj2z1vCLsYkBXAyUC+Y0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=F6PsMU92weqMNwPyDMdRA/PgTO2x8e7z+7DaninK9E8lpDvzhsTMQVyfP08twXtnfd LtSqt/4dE/Bd6o1lz4OedYBCYZ/+vYRJwX+C+EFLv1EtikDoyqnyQdtls9K/bB5A3nbN 2OUlqk3NDiuujbTzoVKcBMm8E/PFTy9FqAaxg= Received: by 10.204.10.149 with SMTP id p21mr5710420bkp.3.1260103038834; Sun, 06 Dec 2009 04:37:18 -0800 (PST) Received: from mavbook.mavhome.dp.ua (pc.mavhome.dp.ua [212.86.226.226]) by mx.google.com with ESMTPS id 16sm1628689fxm.12.2009.12.06.04.37.17 (version=SSLv3 cipher=RC4-MD5); Sun, 06 Dec 2009 04:37:18 -0800 (PST) Sender: Alexander Motin Message-ID: <4B1BA57B.4070302@FreeBSD.org> Date: Sun, 06 Dec 2009 14:37:15 +0200 From: Alexander Motin User-Agent: Thunderbird 2.0.0.23 (X11/20090901) MIME-Version: 1.0 To: Roman Divacky References: <200912060010.nB60AD12004058@svn.freebsd.org> <20091206115119.GA25721@freebsd.org> In-Reply-To: <20091206115119.GA25721@freebsd.org> X-Enigmail-Version: 0.96.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r200171 - in head: sbin/atacontrol sys/arm/mv sys/cam/ata sys/cam/scsi sys/conf sys/dev/ata sys/dev/ata/chipsets sys/powerpc/powermac sys/powerpc/psim X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 06 Dec 2009 12:37:20 -0000 Roman Divacky wrote: > On Sun, Dec 06, 2009 at 12:10:13AM +0000, Alexander Motin wrote: >> Author: mav >> Date: Sun Dec 6 00:10:13 2009 >> New Revision: 200171 >> URL: http://svn.freebsd.org/changeset/base/200171 >> >> Log: >> MFp4: >> Introduce ATA_CAM kernel option, turning ata(4) controller drivers into >> cam(4) interface modules. When enabled, this options deprecates all ata(4) >> peripheral drivers (ad, acd, ...) and interfaces and allows cam(4) drivers >> (ada, cd, ...) and interfaces to be natively used instead. >> >> As side effect of this, ata(4) mode setting code was completely rewritten >> to make controller API more strict and permit above change. While doing >> this, SATA revision was separated from PATA mode. It allows DMA-incapable >> SATA devices to operate and makes hw.ata.atapi_dma tunable work again. >> >> Also allow ata(4) controller drivers (except some specific or broken ones) >> to handle larger data transfers. Previous constraint of 64K was artificial >> and is not really required by PCI ATA BM specification or hardware. > > are there any performance benefits of the 64K limit removal? Yes, but it depends on drive and controller. Also it reduces interrupt rate, CPU and command overhead. Also I prefer to have single system-wide tunable for this (MAXPHYS), instead of absolutely ungrounded hardcoded limitation in every driver. -- Alexander Motin