From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helmut Toplitzer Subject: Re: BUG?: VIA IDE transfer-rate problem Date: Thu, 19 Jan 2006 00:41:35 +0100 Message-ID: <200601190041.36138.pvrusb2@toplitzer.net> References: <200601131909.07981.pvrusb2@toplitzer.net> <200601181536.16868.pvrusb2@toplitzer.net> <58cb370e0601180813pfb6baffr953e5be26223ea1@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from toplitzer.net ([83.151.30.110]:47751 "EHLO toplitzer.net") by vger.kernel.org with ESMTP id S1030461AbWARXlp (ORCPT ); Wed, 18 Jan 2006 18:41:45 -0500 In-Reply-To: <58cb370e0601180813pfb6baffr953e5be26223ea1@mail.gmail.com> Content-Disposition: inline Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Bartlomiej Zolnierkiewicz Cc: linux-ide@vger.kernel.org, dbrownell@users.sourceforge.net, linux-usb-devel@lists.sourceforge.net > > Did disabling ACPI change something? > No, it didn't > > When CPU is idle HLT instruction is used by default (for power saving). > Probably chipset detects when CPU is entering low power mode and > also enters low power mode. Switching between low and normal power > modes is slow and results in degraded performance. > > The question is whether/how we can program chipset to not enter > low power mode. > Ok. Was just a bit digging through the sourcecode. Found a function called disable_hlt. Some further digging. Found in drivers/block/floppy.c a usage of disable_hlt. It's called (if I haven't missunderstood something) whenever a DMA transfer is setup. enable_hlt is called when a transfer stops/is cancled etc... Does such thing makes sense for IDE DMA-transfers too? (Maybe I've missed something) Cheers Helmut -- My GNUpg fingerprint http://www.gnupg.org 4563 F4FB 0B7E 8698 53CD 00E9 E319 35BD 6A91 1656