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Message-ID: <18302.5940.173422.967902@harpo.it.uu.se>
Date: Fri, 4 Jan 2008 12:23:32 +0100
From: Mikael Pettersson <mikpe@it.uu.se>
To: Linda Walsh <lkml@tlinx.org>
Cc: Mikael Pettersson <mikpe@it.uu.se>, LKML <linux-kernel@vger.kernel.org>,
       Robert Hancock <hancockr@shaw.ca>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       linux-ide@vger.kernel.org
Subject: Re: Re:Believed resolved: SATA kern-buffRd read slow: based on promise
 driver bug
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Linda Walsh writes:
 > Mikael Pettersson wrote:
 > > Linda Walsh writes:
 > >  > Robert Hancock wrote:
 > >  > > Linda Walsh wrote:
 > >  > >>>> read rate began falling; at 128k block-reads-at-a-time or larger, it 
 > >  > >>>> drops below 20MB/s (only on buffered SATA).
 > >  > 
 > >  > But more importantly -- I notice a chronic error message associate
 > >  > with this drive that may be causing some or all of the problem:
 > >  > ---
 > >  > ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2
 > >  > ata1.00: port_status 0x20080000
 > >  > ata1.00: cmd c8/00:10:30:06:03/00:00:00:00:00/e0 tag 0 cdb 0x0 data 8192 in
 > >  >          res 50/00:00:3f:06:03/00:00:00:00:00/e0 Emask 0x2 (HSM violation)
 > >  > ata1: limiting SATA link speed to 1.5 Gbps
 > >
 > >
 > > Looks like the Promise ASIC SG bug. Apply
 > > <http://user.it.uu.se/~mikpe/linux/patches/sata_promise/patch-sata_promise-1-asic-sg-bug-fix-v3-2.6.23>
 > > and let us know if things improve.
 > >
 > > /Mikael
 > >   
 > ---
 >     Yep!  Hope that's making it into a patch soon or, at least 2.6.24.
 >     Kernel buffered

Good to hear that it solved this problem.
The patch is in 2.6.24-rc2 and newer kernels, and will be sent
to -stable for the 2.6.23 and 2.6.22 series.

 >     I seem to remember reading about some problems with Promise SATA & ACPI.
 > Does this address that or is that a separate issue?  (Am using no-acpi for

sata_promise does nothing ACPI-related. It doesn't need to.
(Drives may be a different story.)

 >     Is the above bug mentioned/discussed in the linux-ide archives?

Yes.

 >  That
 > and I'd like to find out why TCQ/NCQ doesn't work with the Seagate drives --

The driver doesn't yet support NCQ.