From owner-freebsd-hackers Thu May 24 15: 6:53 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from mail.matriplex.com (ns1.matriplex.com [208.131.42.8]) by hub.freebsd.org (Postfix) with ESMTP id 29D1437B422 for ; Thu, 24 May 2001 15:06:50 -0700 (PDT) (envelope-from rh@matriplex.com) Received: from mail.matriplex.com (mail.matriplex.com [208.131.42.9]) by mail.matriplex.com (8.9.2/8.9.2) with ESMTP id PAA77102 for ; Thu, 24 May 2001 15:06:37 -0700 (PDT) (envelope-from rh@matriplex.com) Date: Thu, 24 May 2001 15:06:37 -0700 (PDT) From: Richard Hodges To: hackers@FreeBSD.ORG Subject: Knob for ATA maximum UDMA? Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG I was just testing out a new configuration, when I get two of these about an hour apart, and then another today: ts8 /kernel: ad4: READ command timeout tag=0 serv=0 - resetting ts8 /kernel: ata2: resetting devices .. done Needless to say, this is a problem. Here is the boot info: ts8 /kernel: ad0: 29311MB [59554/16/63] at ata0-master UDMA66 ts8 /kernel: ad3: 29311MB [59554/16/63] at ata1-slave UDMA66 ts8 /kernel: ad4: 29311MB [59554/16/63] at ata2-master UDMA100 ts8 /kernel: ad5: 29311MB [59554/16/63] at ata2-slave UDMA100 The first two are on a VIA 82C686 bridge, the second two are HPT370. I am wondering if UDMA100 is just too much for the cabling, and am interested in finding out whether running them all at UDMA33 would provide an extra safety margin. I see in dev/ata/ata-dma.c, ata_dmainit() checks some cable flag, and reduces the UDMA capability to UDMA33 if neccessary. This seems like a decent place to hardwire it for testing. Is there any other place that also needs to be changed? If there actually is a difference in stability, would anyone favor a new sysctl to put an arbitrary cap on the UDMA capabilities? As far as I can tell, there should not be ANY performance difference between UDMA100 and UDMA66, or even with UDMA33 if there is only one drive per cable. Comments and suggestions are appreciated :-) -Richard ------------------------------------------- Richard Hodges | Matriplex, inc. Product Manager | 769 Basque Way rh@matriplex.com | Carson City, NV 89706 775-886-6477 | www.matriplex.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message