Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755471AbYAACOs (ORCPT ); Mon, 31 Dec 2007 21:14:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754643AbYAACIo (ORCPT ); Mon, 31 Dec 2007 21:08:44 -0500 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:54338 "EHLO the-village.bc.nu" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754633AbYAACIm (ORCPT ); Mon, 31 Dec 2007 21:08:42 -0500 Date: Tue, 1 Jan 2008 01:58:12 +0000 From: Alan Cox To: Linda Walsh Cc: Robert Hancock , LKML Subject: Re: SATA kernel-buffered read VERY slow (not raid, Promise TX300 card); 2.6.23.1(vanilla) Message-ID: <20080101015812.59e9ebf0@the-village.bc.nu> In-Reply-To: <4779870E.5070507@tlinx.org> References: <4777E08C.4000603@shaw.ca> <4779870E.5070507@tlinx.org> X-Mailer: Claws Mail 3.1.0 (GTK+ 2.10.14; i386-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1817 Lines: 45 > rate began falling and at 128k block-reads-at-a-time or larger, it drops > below > 20MB/s (again, only on buffered SATA). It's hard to imagine what would > slow down buffered SATA reads but not ATA and SCSI reads of the same > size. I'm using the 'cfq' scheduler with everything running at default Try disabling NCQ - see if you've got a drive with the 'NCQ = no readahead' flaw. > priorities, but again, why only SATA slowness? It seems that at the driver > level, using direct reads, the SATA disk has the highest read rate (near > 80MB/s). Beats me - something is wrong that your setup triggers - could be firmware funnies or Linux ones. > The only way I could tell before was using hdparm to read the > parameters. > Since that doesn't work, it's hard to tell if they are set correctly, > but given hdparm supports identify to read modes on drives with libata. The one thing you cannot do is force modes right now. > More importantly, how does one set parameters for acoustic and power > saving parameters? Some of my disks are used as 'backup' devices for my hdparm or blktool > other computers. With the ATA disks, they were kept "spun down" when not > being used (only used, 'normally', in early AM hours). Well for backup devices you can use the fact SATA is hot/warm plug. > Another new "problem" (not as important) -- even though SATA disks are > called with "sdX", my ATA disks that *were* at hda-hdc are now at hde-hdg. NOTABUG - your BIOS has decided to move them from the legacy addresses so they move from hda-d to e-g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/