From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264182AbTDPJT7 (for ); Wed, 16 Apr 2003 05:19:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264190AbTDPJT7 (for ); Wed, 16 Apr 2003 05:19:59 -0400 Received: from c-97a870d5.037-69-73746f23.cust.bredbandsbolaget.se ([213.112.168.151]:22401 "EHLO zaphod.guide") by vger.kernel.org with ESMTP id S264182AbTDPJT6 (for ); Wed, 16 Apr 2003 05:19:58 -0400 To: Ivan Kokshaysky Cc: Alan Cox , Linux Kernel Mailing List Subject: Re: DMA transfers in 2.5.67 References: <1050438684.28586.8.camel@dhcp22.swansea.linux.org.uk> <1050439715.28586.17.camel@dhcp22.swansea.linux.org.uk> <20030416123654.A2629@jurassic.park.msu.ru> From: mru@users.sourceforge.net (=?iso-8859-1?q?M=E5ns_Rullg=E5rd?=) Date: 16 Apr 2003 11:30:43 +0200 In-Reply-To: Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) XEmacs/21.4 (Portable Code) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org mru@users.sourceforge.net (Måns Rullgård) writes: > > > > Btw, I just noticed that hard disk throughput is much lower with 2.5 > > > > than 2.4. With 2.4.21-pre5 I get ~40 MB/s, but with 2.5.67 the speed > > > > drops to 25-30 MB/s. Everything according to hdparm. Is it possible > > > > that DMA is generally slow for some reason? > > > > > > Possible reason is that in 2.4 we've forced reasonable latency timer > > > value for all PCI devices, while in 2.5 we haven't as yet. > > > > Do you mean whatever causes this message (for a 3com NIC)? > > > > PCI: Setting latency timer of device 00:05.0 to 64 > > > > Would that also explain why my hard disks are slow under 2.5? There > > is no corresponding message for the ide controller (htp374). > > I just checked the troublesome board. Here's what lspci has to say: > > 00:06.0 Display controller: 3DLabs GLINT R3 (rev 01) > Subsystem: 3DLabs: Unknown device 0121 > Flags: bus master, 66Mhz, medium devsel, latency 0, IRQ 27 > Memory at 0000000009020000 (32-bit, non-prefetchable) [size=128K] > Memory at 000000000c000000 (32-bit, prefetchable) [size=64M] > Memory at 0000000010000000 (32-bit, prefetchable) [size=64M] > Expansion ROM at 0000000009060000 [disabled] [size=64K] > Capabilities: > > The latency 0 doesn't look too good. What should I do to change it? I set the latency to 128 using setpci and now I get 66 MB/s. Other values give slower transfer rates. Is there some other setting that could improve it even more? -- Måns Rullgård mru@users.sf.net