From owner-freebsd-current  Thu Feb  6 23:20:15 2003
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From: Soeren Schmidt <sos@spider.deepcore.dk>
Message-Id: <200302070720.h177K9dG030735@spider.deepcore.dk>
Subject: Re: ATA code is buggy and slower
In-Reply-To: <3E43248F.2030303@plan9.bell-labs.com>
To: Dong Lin <dong@plan9.bell-labs.com>
Date: Fri, 7 Feb 2003 08:20:09 +0100 (CET)
Cc: current@FreeBSD.ORG
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It seems Dong Lin wrote:
> 
> My 5.0R kernel complains about "READ timeout" and "resetting" when I try 
> to dd the disk. But everything *works* if I boot the same equipment with 
> 4.5R and 4.7R. It seems that the error can occur on any sector I pick as 
> long as I keep reading it inside a loop, a sign of timing problems.
> 
> The 5.0 ATA code is so different that I am not sure where to start. If 
> someone can show me a way to run the 4.7 ATA code under 5.0, I am 
> willing to debug it.
> 
> My equipment: Promise ATA66 controller(0x4d38105a r01), WDC WD400BB 
> ATA/100, ATA66 cable.
> 
> Also, my simple dd measurements show that performance is going down:
> 
> dd if=/dev/ad4 of=/dev/null bs=8m
> 4.5R:	49 MB/s
> 4.7R:	39 MB/s
> 5.0R:	does not finish

Grap the ATA driver (sys/dev/ata) from -currrent, there is a bug 
in the 48bit support code for old promises thats not fixed in 5.0.

-Søren

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