From owner-freebsd-hackers Wed Mar 22 07:54:09 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id HAA07609 for hackers-outgoing; Wed, 22 Mar 1995 07:54:09 -0800 Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.34]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id HAA07598; Wed, 22 Mar 1995 07:53:57 -0800 Received: (from bde@localhost) by godzilla.zeta.org.au (8.6.9/8.6.9) id BAA17998; Thu, 23 Mar 1995 01:13:13 +1000 Date: Thu, 23 Mar 1995 01:13:13 +1000 From: Bruce Evans Message-Id: <199503221513.BAA17998@godzilla.zeta.org.au> To: bde@zeta.org.au, sos@login.dknet.dk Subject: Re: Why IDE is bad Cc: faq@FreeBSD.org, hackers@FreeBSD.org, hasty@star-gate.com, phk@ref.tfs.com Sender: hackers-owner@FreeBSD.org Precedence: bulk >> >And that is the main thing on E-IDE, the drives are designed >> >with enough onboard cache, that coretest etc. reports transfer >> >rates close to the interface speed (13MB sec or so), but the >> >drive cannot hold this speed when it has to read from the media. >> >> This is also good for reducing interrupt overhead. >Hmm, most of the drives would intterupt once each sector anyway >even when doing DMA, so there is really nothing gained... Interrupts don't take long (< 10 usec on a DX2/66) if the driver doesn't do anything. The IDE driver does a lot. It takes at least 155 usec to transfer 512 bytes at 3.3MB/sec. Dividing `a lot' by (11.3/3.3) has good effects. >> I expect better IDE drives would have been avaiable if the >> interface had supported them. >Actually I think not, the IDE thing is about making CHEAP disks >for the average PC user. It is much better advertising to have a >500MB drive than a 300MB drive, who cares about performance ??? "Only" half the posters in comp.sys.ibm.pc.hardware.*. Even the average user needs ever increasing performance to run the latest bloatware. Bruce