From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 28 May 2001 18:11:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 28 May 2001 18:11:46 -0400 Received: from Sarah.SomeSites.com ([208.44.57.7]:53514 "HELO MoveAlong.SomeSites.com") by vger.kernel.org with SMTP id ; Mon, 28 May 2001 18:11:38 -0400 Message-ID: <002101c0e7c3$18cdbfb0$0100a8c0@SomeSites.com> From: "James Turinsky" To: "Mark Hahn" , "Alan Cox" Cc: "Jens Axboe" , , In-Reply-To: Subject: Re: [patch]: ide dma timeout retry in pio Date: Mon, 28 May 2001 18:11:05 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ----- Original Message ----- From: "Alan Cox" To: "Mark Hahn" Cc: "Jens Axboe" ; ; ; Sent: Monday, May 28, 2001 5:12 PM Subject: Re: [patch]: ide dma timeout retry in pio > > really? do we know the nature of the DMA engine problem well enough? > > I can categorise some of them: > > 1. Hardware that just doesnt support it. > 2. Timeouts that are false positives caused by disks having problems > and being very slow to recover > 3. Bad cabling > 4. Stalls caused by heavy PCI traffic > > > is there a reason to believe that it'll work better "later"? > > #1 will go fail, fail, fail -> PIO now (or should do Im about to try it) > #2 and #4 will be transient > #3 could go either way Where does the "'DMA Timeout -> disable DMA' then lose all responsiveness when I issue 'hdparm -d1' while it tries and fails to re-enable DMA" fit in? The disk will happily run for several days in UDMA33 and then at some point it craps out with a DMA timeout which results 1) DMA being turned off and 2) all attempts to re-enable DMA failing? And what's up with this: [root@MoveAlong james]# hdparm /dev/hda /dev/hda: multcount = 0 (off) I/O support = 1 (32-bit) unmaskirq = 1 (on) using_dma = 1 (on) keepsettings = 1 (on) nowerr = 0 (off) readonly = 0 (off) readahead = 8 (on) geometry = 19590/16/63, sectors = 19746720, start = 0 [root@MoveAlong james]# hdparm -tT /dev/hda /dev/hda: Timing buffer-cache reads: 128 MB in 6.98 seconds = 18.34 MB/sec Timing buffered disk reads: 64 MB in 5.77 seconds = 11.09 MB/sec Hmm.. suspicious results: probably not enough free memory for a proper test. [root@MoveAlong james]# free total used free shared buffers cached Mem: 126800 123460 3340 0 67284 41572 -/+ buffers/cache: 14604 112196 Swap: 394624 32816 361808 I used to get ~33MB/sec on buffer-cache and ~10MB/sec on buffered disk reads in 2.2... --JT