The following reply was made to PR port-i386/33585; it has been noted by GNATS.

From: Abrasive <abrasive@axdf.net>
To: gnats-bugs@NetBSD.org, bouyer@antioche.eu.org
Cc: 
Subject: Re: port-i386/33585: piixide interrupt thrashing on SATA interface
Date: Fri, 2 Jun 2006 12:24:13 +1000

 There certainly is one interrupt per transfer... however, today, for some reason, the CPU is no longer spending all its time servicing interrupts, even at 600 per second.
 I must conclude that something else, like a USB driver, was trying to service them and timing out before passing the interrupt to the disk driver.
 
 Apologies for the misdiagnosis; last time I saw the same symptoms it was a DMA problem.
 
 Thanks for the help; I'll keep poking until I figure out what interferes with what.
 
 James.