From owner-cvs-src@FreeBSD.ORG Tue Apr 8 10:26:06 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8172D37B407; Tue, 8 Apr 2003 10:26:06 -0700 (PDT) Received: from freebie.xs4all.nl (freebie.xs4all.nl [213.84.32.253]) by mx1.FreeBSD.org (Postfix) with ESMTP id E40A043FBF; Tue, 8 Apr 2003 10:26:02 -0700 (PDT) (envelope-from wkb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (localhost [127.0.0.1]) by freebie.xs4all.nl (8.12.9/8.12.9) with ESMTP id h38HPtpH009601; Tue, 8 Apr 2003 19:25:55 +0200 (CEST) (envelope-from wkb@freebie.xs4all.nl) Received: (from wkb@localhost) by freebie.xs4all.nl (8.12.9/8.12.9/Submit) id h38HPtSL009600; Tue, 8 Apr 2003 19:25:55 +0200 (CEST) Date: Tue, 8 Apr 2003 19:25:55 +0200 From: Wilko Bulte To: Dag-Erling Smorgrav Message-ID: <20030408172555.GA9572@freebie.xs4all.nl> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-OS: FreeBSD 4.8-STABLE X-PGP: finger wilko@freebsd.org cc: src-committers@FreeBSD.ORG cc: cvs-src@FreeBSD.ORG cc: Alexander Leidinger cc: Nate Lawson cc: sos@spider.deepcore.dk cc: cvs-all@FreeBSD.ORG cc: sos@FreeBSD.ORG Subject: Re: cvs commit: src/sys/dev/ata ata-all.c ata-all.h ata-chipset.cata-dma.c ata-pci.c ata-pci.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Apr 2003 17:26:07 -0000 On Tue, Apr 08, 2003 at 07:15:04PM +0200, Dag-Erling Smorgrav wrote: > Nate Lawson writes: > > Tagged queuing is orthogonal to caching. TQ allows multiple transactions > > to be passed to the drive, allowing it to order and aggregate the requests > > as it thinks best. TQ can be done with no cache because all the drive is > > tracking is handles to transactions (typically 16 bit ids). Think of it > > as more like a pipeline than a cache. > > It can't be done without cache, because you can't queue and reorder > transactions without some sort of cache. But you could do read buffering (to avoid the C word) only, so no write cache which has the volatility issues which have been discussed over and over again in combination with ATA drives. I still don't get it why ATA drives cannot be built to the same spec as SCSI drives as far as write caching etc are concerned Probably cost ;) ATA is for el-cheapo stuff. Serial ATA might see new uses, say in arrays. W/ -- | / o / /_ _ wilko@FreeBSD.org |/|/ / / /( (_) Bulte