Xen devel - Mar 2012 - Re: quick question re blkback/blkfront w/ Xen 4.1.2

On Tue, Feb 28, 2012 at 04:41:44PM -0800, Steven Noonan
wrote:
> With a PV guest on Xen 4.1.2 (Linux 3.2.2 dom0), I''m noticing that
while
> block I/O is happening the event channel interrupt count in
> dom0:/proc/interrupts isn''t incrementing at all. How can this be?
Hey Steven,

Sorry about late response - was on paternity leave (and is a bit this
week). I am CC-ing the xen-devel on this.

I tried it and the numbers do seem to increment on my side.
You were looking at the blkif numbers right? Is this with a 2.6.18 guest
or a 3.2?
> 
> - Steven

On Mon, Mar 19, 2012 at 10:43 AM, Konrad Rzeszutek Wilk
<konrad.wilk@oracle.com> wrote:
> On Tue, Feb 28, 2012 at 04:41:44PM -0800, Steven Noonan wrote:
>> With a PV guest on Xen 4.1.2 (Linux 3.2.2 dom0), I''m noticing
that while
>> block I/O is happening the event channel interrupt count in
>> dom0:/proc/interrupts isn''t incrementing at all. How can this
be?
>
> Hey Steven,
>
> Sorry about late response - was on paternity leave (and is a bit this
> week). I am CC-ing the xen-devel on this.
>
> I tried it and the numbers do seem to increment on my side.
> You were looking at the blkif numbers right? Is this with a 2.6.18 guest
> or a 3.2?
>
Yeah, I got your message about paternity leave. Congrats! :)

It''s a Linux 3.2 dom0 (I believe it''s untouched vanilla) and
Linux 3.2
domU (Ubuntu 12.04 beta, with 3.2.0-based Ubuntu kernel, PV).

And yes, blkif-backend. It''s strange, because I/O seems to happen just
fine (and it''s definitely not going through QEMU, since it''s a
PV
guest and the devices are clearly registered as VBDs), but the
interrupt counts are frozen.

On Mon, Mar 19, 2012 at 10:51:22AM -0700, Steven Noonan
wrote:
> On Mon, Mar 19, 2012 at 10:43 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Tue, Feb 28, 2012 at 04:41:44PM -0800, Steven Noonan wrote:
> >> With a PV guest on Xen 4.1.2 (Linux 3.2.2 dom0), I''m
noticing that while
> >> block I/O is happening the event channel interrupt count in
> >> dom0:/proc/interrupts isn''t incrementing at all. How can
this be?
> >
> > Hey Steven,
> >
> > Sorry about late response - was on paternity leave (and is a bit this
> > week). I am CC-ing the xen-devel on this.
> >
> > I tried it and the numbers do seem to increment on my side.
> > You were looking at the blkif numbers right? Is this with a 2.6.18
guest
> > or a 3.2?
> >
> 
> Yeah, I got your message about paternity leave. Congrats! :)
> 
> It''s a Linux 3.2 dom0 (I believe it''s untouched vanilla)
and Linux 3.2
> domU (Ubuntu 12.04 beta, with 3.2.0-based Ubuntu kernel, PV).
OK, let me try to reproduce this.
> 
> And yes, blkif-backend. It''s strange, because I/O seems to happen
just
> fine (and it''s definitely not going through QEMU, since
it''s a PV
> guest and the devices are clearly registered as VBDs), but the
> interrupt counts are frozen.
> 
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