From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 28 Jul 2002 04:59:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 28 Jul 2002 04:59:55 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:775 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id ; Sun, 28 Jul 2002 04:59:53 -0400 Message-ID: <3D43B54C.E33BF47F@zip.com.au> Date: Sun, 28 Jul 2002 02:11:40 -0700 From: Andrew Morton X-Mailer: Mozilla 4.79 [en] (X11; U; Linux 2.4.19-rc3-ac3 i686) X-Accept-Language: en MIME-Version: 1.0 To: lkml Subject: Re: [patch 12/13] direct IO updates References: <3D439E47.A227A2B7@zip.com.au> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > > ... > > And against four IDE disks on an HPT374 controller. Throughput is 120 > megabytes/sec: > > c01eed8c 80 0.292462 end_that_request_first > c01fe850 87 0.318052 hpt3xx_intrproc > c01ed574 123 0.44966 blk_rq_map_sg > c01f8f10 141 0.515464 ata_select > c014db38 153 0.559333 do_direct_IO > c010bb78 235 0.859107 timer_interrupt > c01f9144 281 1.02727 ata_irq_enable > c01ff990 290 1.06017 udma_pci_init > c01fe878 308 1.12598 hpt3xx_maskproc > c02006f8 379 1.38554 idedisk_do_request > c02356a0 609 2.22637 pci_conf1_read > c01ff8dc 611 2.23368 udma_pci_start > c01ff950 922 3.37062 udma_pci_irq_status > c01f8fac 1002 3.66308 ata_status > c01ff26c 1059 3.87146 ata_start_dma > c01feb70 1141 4.17124 hpt374_udma_stop > c01f9228 3072 11.2305 ata_out_regfile > c01052d8 15193 55.5422 poll_idle > > Not so good. Actually... The adaptecs are on different PCI buses, so there is plenty of spare PCI capacity. The HPT374 is on a single 33MHz/32bit PCI bus, which is saturated. So CPU access to the IDE controller registers will be contending with all that busmastering traffic, which may explain a lot of this difference. -