Re: megasas stops I/O when running kernel as dom0 under xen4.1/4.2

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 30/08/11 13:02, Andreas Olsowski wrote:
> --snip--
> > Apologies - previous patch fails to compile (i forgot to hg qrefresh
> > before sending - it has been a very long day).  Try this patch.
> Testing right now, so far it seems to do fine, patching worked, so did
> compilation.
>
> A scenario that previously stopped io does no longer stop it.
>
> Ill give it a couple of more tries and days, but it sure looks good.
>
> Any chance of introducing this patch into xen-4.1-testing and making
> it a part of the upcoming xen-4.1.2?
>
>
> with best regards,
>
> Andreas
>

That is up to Keir.  My opinion is that this patch is more of a hack
than a solution, especially as it does involve changing the API for
interrupt ops, but that does not necessarily prevent it from being included.

I will soon be working on some significant changes to the interrupt code
(cleanup of structures, cleanup of logic - specifically the logic which
is now false with per-cpu IDTs) with an intension to upstream them, but
whether these patches are suitable to backport is an entirely different
question.


On a completely different note, we have got in contact with LSI who are
altering their driver to consider MSI interrupts as well as MSI-X
interrupts, which will be sensible to take, as MSI interrupts will give
you an order of magnitude faster disk IO, irrespective of the line level
bug in Xen.

~Andrew

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com