From owner-freebsd-hackers Tue Jun 3 08:52:50 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id IAA05486 for hackers-outgoing; Tue, 3 Jun 1997 08:52:50 -0700 (PDT) Received: from sos.freebsd.dk (sos.freebsd.dk [195.8.129.33]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id IAA05480 for ; Tue, 3 Jun 1997 08:52:45 -0700 (PDT) Received: (from sos@localhost) by sos.freebsd.dk (8.8.5/8.7.3) id RAA10984; Tue, 3 Jun 1997 17:52:38 +0200 (MEST) From: Søren Schmidt Message-Id: <199706031552.RAA10984@sos.freebsd.dk> Subject: Re: DMA for IDE drives ? In-Reply-To: <199706031502.JAA04331@pluto.plutotech.com> from "Justin T. Gibbs" at "Jun 3, 97 09:58:58 am" To: gibbs@plutotech.com (Justin T. Gibbs) Date: Tue, 3 Jun 1997 17:52:38 +0200 (MEST) Cc: luigi@labinfo.iet.unipi.it, toor@dyson.iquest.net, hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL30 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk In reply to Justin T. Gibbs who wrote: > Do the newer IDE drives support any concept similar to tagged queueing? > Perhaps via EATA? Supporting DMA is only half the battle in my mind as you > won't get anywhere near the throughput of a SCSI drive if you can't > schedule and have the drive reorder multiple transactions at a time. There seems to be provision for queued overlapped DMA in the newest ATA pseudo std. A depth up to 31 is possible. I havn't checked deeper yet what the drives are capable of doing with the queue though... I'm currently playing with using DMA on my Maxtor drives, I'll look closer when I get the time.... -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Søren Schmidt (sos@FreeBSD.org) FreeBSD Core Team Even more code to hack -- will it ever end ..