Karl Denninger karl at denninger.net
Wed Mar 30 16:24:55 PST 2005

On Wed, Mar 30, 2005 at 12:06:11AM -0600, Karl Denninger wrote:
> On Wed, Mar 30, 2005 at 12:50:31AM -0500, Matthew N. Dodd wrote:
> > On Tue, 29 Mar 2005, Karl Denninger wrote:
> > > 245a252
> > >>           request->donecount = 0;
> > >
> > > Without the last delta the requeue doesn't happen at all.
> > 
> > So you're saying that this change:
> > 
> >  	1.42: When resubmitting a timed out request, reset donecount.
> > 
> > produces the problem?
> I believe so, yes, if my recollection from earlier in the month is correct.
> Without it, the problem doesn't exist, but the requeueing doesn't happen
> either (well technically according to the code it does, but it doesn't do
> anything) - so whether that's the problem or whether it simply MASKS the
> problem I can't say without further investigation.
> I am loading up my sandbox machine with an exact copy now, and expect to
> know more sometime tomorrow - I will have to go through a full
> buildworld/installworld/buildkernel/installkernel to bring the sandbox up 
> to date and then stuff a SATA disk and adapter in there to re-create the
> environment closely enough to be sure that I'm looking at the same issue.
> More as soon as I know with certainty.

It appears that the change was backed out of the CVS tree late last night.

I've reproduced the original problem on my sandbox, and am now testing
removing the patch lines one at a time.  Hopefully I can isolate exactly
which line causes trouble.

BTW, it appears that the original problem (DMA write errorrs) ONLY occur if
you have at least two SATA devices - at least in my system - and at least
one of them is on the SI chipset.  

A single UDMA100 PATA disk and a single SATA150 disk DO NOT trigger retries,
no matter how high the load.  Had to diddle with things to get it to go
"bang" so I can isolate....

Hopefully more this evening - first round (removing the "!" change) being
run now.

Karl Denninger (karl at denninger.net) Internet Consultant & Kids Rights Activist
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