Rafael J. Wysocki wrote:
> On Friday, July 09, 2010, Stephan Diestelhorst wrote:
> > I wrote:
> > >   I have an issue with suspend to RAM and I/O load on a disk. Symptoms
> > > are that the disk does not respond to requests when woken up, producing
> > > only I/O errors on all tested kernels (newest 2.6.35-rc4 (Ubuntu
> > > mainline PPA build)):
> > > 
> > <snip>
> >  
> > > This can be triggered most reliably with multiple "direct" writes to
> > > disk, I create the load with the attached script. If the issue is
> > > triggered, suspend (through pm-suspend) takes very long.
> > 
> > > IMHO the interesting log output during suspend is:
> > > [ 1674.700125] ata1.00: qc timeout (cmd 0xec)
> > 
> > Almighty google suggested to try "pci=nomsi", which seems to have
> > cured the issue for me for now. Is that plausible? I'll keep this
> > under observation.
> 
> Hmm.  How does your /proc/interrupts look like?

This has been yet another red herring. After trying out the kernel
option three times with two different kernels, it failed yet again
with the same symptoms. 

I have attached /proc/interrupts for 2.6.35-rc4, once with pci=nomsi
and once without, but again, I do not think this makes a difference :-/

> Also, do you have a link to this "Google suggestion"?

It was some german forum, a guy with completely different HW, but the
same symptom. I thought trying out the option wouldn't hurt.

Maybe it came for example from http://lkml.org/lkml/2008/12/20/3
originally.

Stephan