From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Furness Subject: IDE tuning - How? Date: 04 Apr 2003 10:33:05 +0100 Sender: linux-admin-owner@vger.kernel.org Message-ID: <1049448784.2176.22.camel@zebra.vil.ite.mee.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-admin@vger.kernel.org Hi. Can anyone tell me how to tell the linux kernel that my IDE hard disk and interface are ATA133 not ATA100? I first noticed a problem after installing Debian on my development system. The install took ages, but after the install the whole system was very jerky and slow (this was on a P4 1.9G with lots of memory, so I figured it wasn't CPU problems. Top confirmed this). Further investigation showed that it was only slow when accessing the hard disk. hdparm -t /dev/hda told me that it was going at between 3 and 4 M/s which is scarily slow. I looked carefully through the boot messages, and came across "assuming IDE bus speed 33MHz. override with idebus=xx" (Sorry, the wording might be a little different but the message was essentially that). I therefore added "idebus=66" to my kernel boot up line in grub.conf, and sure enough it booted and told me "assuming IDE bus speed 66MHz." According to hdparm, it is now giving me around 40MB/s, which is a definite improvement. So far so good. But then I noticed that is detects the hard disk as ATA100. I know it's a 133, as I only bought it recently and I know what model I bought (Diamond max +9 120GB ATA133). I am assuming (possibly naively) that if the IDE module in the kernel is only using 100, I'm only getting about 66% of the performance I should. ( I know, nothing's ever linear...) I tried adding "ide0=ata133" to the kernel params, but it makes no difference. The IDE code documentation doesn't seem to help beyond telling me to do what I have already tried. Am I missing something obvious? Paul.