Date: Mon, 21 May 2007 22:04:26 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Stephen Hemminger <shemminger@linux-foundation.org>
cc: Jeff Garzik <jeff@garzik.org>, Mike Houston <mikeserv@bmts.com>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Linux 2.6.22-rc2
In-Reply-To: <20070521214255.3dc36445@freepuppy>
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On Mon, 21 May 2007, Stephen Hemminger wrote:
>
> AHCI on this motherboard doesn't seem to use MSI. The problems occur
> even if I boot with nomsi.

Have you tried playing with PCI latency counters etc? 

Maybe the SATA/AHCI thing is better at saturating the bus, and the sky2 
hardware gets upset if it has overlong DMA access latencies due to some 
other controller keeping the bus busy with a long burst access?

I can't really see that being a real problem in this day and age of PCI-X 
etc, but it _used_ to be a possible issue a decade ago. Maybe you've found 
a case where it matters even on modern hardware? We occasionally used to 
set the PCI latency timer to make people happy.

(Not that I'm convinced it even has any semantic meaning on a modern PCI 
system..)

		Linus
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