Date: Mon, 28 May 2001 10:03:30 +0200 (CEST) From: Søren Schmidt <sos@freebsd.dk> To: Richard Hodges <rh@matriplex.com> Cc: hackers@FreeBSD.ORG Subject: Re: Knob for ATA maximum UDMA? Message-ID: <200105280804.f4S84op02854@freebsd.dk> In-Reply-To: <Pine.BSF.4.10.10105241440210.76082-100000@mail.matriplex.com> "from Richard Hodges at May 24, 2001 03:06:37 pm"
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It seems Richard Hodges wrote: On -current you can set the transfer mode to anything you like (and that the controller/device supports) using atacontrol, so no need to hack the kernel anymore :) > 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 <Maxtor 53073H6> [59554/16/63] at ata0-master UDMA66 > ts8 /kernel: ad3: 29311MB <Maxtor 53073H6> [59554/16/63] at ata1-slave UDMA66 > ts8 /kernel: ad4: 29311MB <Maxtor 53073H6> [59554/16/63] at ata2-master UDMA100 > ts8 /kernel: ad5: 29311MB <Maxtor 53073H6> [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 > -Søren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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